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  • contentoffset during flick gesture

    - by Michael Xu
    Hi all, Does anyone else notice that the contentOffset of UIScrollView doesnt update during a flick gesture? It only updates after the flick gesture has totally completed, when the flick gesture is finished. After the finger has left the screen, the scrollview keeps moving, in the decelerating phase. but this isnt reflected in the contentOffset of the UIScrollView. Is there a way to track where the contentOffset is during the decelerating part of the flick gesture? I have an OpenGL layer on top, and i want it to move with the scrollView. Can't seem to get the right info out of the scrollview though... Thoughts? thanks, michael

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  • How to get UIScrollView contentOffset during an animation

    - by user249488
    I am trying to get the contentOffset property of a UIScrollView in the middle of a setContentOffset animation. Note I am not using the animated property of the method, but instead enclosing the setContentOffset operation within a UIView animation block so I can have finer control. When I try to read the value of contentOffset in the middle of the animation, it returns the final value rather than the value at that moment. I know that you can use the presentationLayer to get the current layer, but is there any way you can get the current offset in the middle of an animation?

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  • How to intercept UIScrollView contentOffset changes from UITableView subclass?

    - by mystify
    Actually, a UITableView is a UIScrollView (inherits from that). Now, I made a UITableView subclass and added this line of code to it: - (void)scrollViewDidScroll:(UIScrollView *)scrollView { NSLog(@"contentOffset: %@", NSStringFromCGPoint(self.contentOffset)); } For some reason this is never called when I scroll the table view. But since UITableView has a delegate property on it's own, I assume that it must implement UIScrollViewDelegate protocol and is the delegate for the scroll view itself. Isn't it? How could I intercept scroll position changes? I want to read them only. Probably I couldn't set them with contentOffset, right?

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  • Animating the offset of the scrollView in a UICollectionView/UITableView causes prematurely disappearing cells

    - by radutzan
    We have a UICollectionView with a custom layout very similar to UITableView (it scrolls vertically). The UICollectionView displays only 3 cells simultaneously, with one of them being the currently active cell: [ 1 ] [*2*] [ 3 ] (The active cell here is #2.) The cells are roughly 280 points high, so only the active cell is fully visible on the screen. The user doesn't directly scroll the view to navigate, instead, she swipes the active cell horizontally to advance to the next cell. We then do some fancy animations and scroll the UICollectionView so the next cell is in the "active" position, thus making it the active one, moving the old one away and bringing up the next cell in the queue: [ 2 ] [*3*] [ 4 ] The problem here is setting the UICollectionView's offset. We currently set it in a UIView animation block (self.collectionView.contentOffset = targetOffset;) along with three other animating properties, which mostly works great, but causes the first cell (the previously active one, in the latter case, #2) to vanish as soon as the animation starts running, even before the delay interval completes. This is definitely not ideal. I've thought of some solutions, but can't figure out the best one: Absurdly enlarge the UICollectionView's frame to fit five cells instead of three, thus forcing it to keep the cells in memory even if they are offscreen. I've tried this and it works, but it sounds like an awfully dirty hack. Take a snapshot of the rendered content of the vanishing cell, put it in a UIImageView, add the UIImageView as a subview of the scrollView just before the cell goes away in the exact same position of the old cell, removing it once the animation ends. Sounds less sucky than the previous option (memory-wise, at least), but still kinda hacky. I also don't know the best way to accomplish this, please point me in the right direction. Switch to UIScrollView's setContentOffset:animated:. We actually used to have this, and it fixed the disappearing cell issue, but running this in parallel with the other UIView animations apparently competes for the attention of the main thread, thus creating a terribly choppy animation on single-core devices (iPhone 3GS/4). It also doesn't allow us to change the duration or easing of the animation, so it feels out of sync with the rest. Still an option if we can find a way to make it work in harmony with the UIView block animations. Switch to UICollectionView's scrollToItemAtIndexPath:atScrollPosition:animated:. Haven't tried this, but it has a big downside: it only takes 3 possible constants (that apply to this case, at least) for the target scroll position: UICollectionViewScrollPositionTop, UICollectionViewScrollPositionCenteredVertically and UICollectionViewScrollPositionBottom. The active cell could vary its height, but it always has to be 35 points from the top of the window, and these options don't provide enough control to accomplish the design. It could also potentially be just as problematic as 3.1. Still an option because there might be a way to go around the scroll position thing that I don't know of, and it might not have the same issue with the main thread, which seems unlikely. Any help will be greatly appreciated. Please ask if you need clarification. Thanks a lot!

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  • Stop UITextView from jumping when programatically setting text

    - by Michael Waterfall
    Hi there, I have to update a small amount of text in a scrolling UITextView. I'll only be inserting a character where the cursor currently is, and I'll be doing this on a press of a button on my navigation bar. My problem is that whenever I call the setText method of the text view, it jumps to the bottom of the text. I've tried using contentOffset and resetting the selectedRange but it doesn't work! Here's my example: // Remember offset and selection CGPoint contentOffset = [entryTextView contentOffset]; NSRange selectedRange = [entryTextView selectedRange]; // Update text entryTextView.text = entryTextView.text; // Try and reset offset and selection [entryTextView setContentOffset:contentOffset animated:NO]; [entryTextView setSelectedRange: selectedRange]; Is there any way you can update the text without any scroll movement at all... as if they'd just typed something on the keyboard? Many thanks, Michael Edit: I've tried using the textViewDidChange: delegate method but it's still not scrolling up to the original location. - (void)textViewDidChange:(UITextView *)textView { if (self.programChanged) { [textView setSelectedRange:self.selectedRange]; [textView setContentOffset:self.contentOffset animated:NO]; self.programChanged = NO; } } - (void)changeButtonPressed:(id)sender { // Remember position self.programChanged = YES; self.contentOffset = [entryTextView contentOffset]; self.selectedRange = [entryTextView selectedRange]; // Update text entryTextView.text = entryTextView.text; }

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  • UIScrollView Infinite Scrolling

    - by Ben Robinson
    I'm attempting to setup a scrollview with infinite (horizontal) scrolling. Scrolling forward is easy - I have implemented scrollViewDidScroll, and when the contentOffset gets near the end I make the scrollview contentsize bigger and add more data into the space (i'll have to deal with the crippling effect this will have later!) My problem is scrolling back - the plan is to see when I get near the beginning of the scroll view, then when I do make the contentsize bigger, move the existing content along, add the new data to the beginning and then - importantly adjust the contentOffset so the data under the view port stays the same. This works perfectly if I scroll slowly (or enable paging) but if I go fast (not even very fast!) it goes mad! Heres the code: - (void) scrollViewDidScroll:(UIScrollView *)scrollView { float pageNumber = scrollView.contentOffset.x / 320; float pageCount = scrollView.contentSize.width / 320; if (pageNumber > pageCount-4) { //Add 10 new pages to end mainScrollView.contentSize = CGSizeMake(mainScrollView.contentSize.width + 3200, mainScrollView.contentSize.height); //add new data here at (320*pageCount, 0); } //*** the problem is here - I use updatingScrollingContent to make sure its only called once (for accurate testing!) if (pageNumber < 4 && !updatingScrollingContent) { updatingScrollingContent = YES; mainScrollView.contentSize = CGSizeMake(mainScrollView.contentSize.width + 3200, mainScrollView.contentSize.height); mainScrollView.contentOffset = CGPointMake(mainScrollView.contentOffset.x + 3200, 0); for (UIView *view in [mainContainerView subviews]) { view.frame = CGRectMake(view.frame.origin.x+3200, view.frame.origin.y, view.frame.size.width, view.frame.size.height); } //add new data here at (0, 0); } //** MY CHECK! NSLog(@"%f", mainScrollView.contentOffset.x); } As the scrolling happens the log reads: 1286.500000 1285.500000 1284.500000 1283.500000 1282.500000 1281.500000 1280.500000 Then, when pageNumber<4 (we're getting near the beginning): 4479.500000 4479.500000 Great! - but the numbers should continue to go down in the 4,000s but the next log entries read: 1278.000000 1277.000000 1276.500000 1275.500000 etc.... Continiuing from where it left off! Just for the record, if scrolled slowly the log reads: 1294.500000 1290.000000 1284.500000 1280.500000 4476.000000 4476.000000 4473.000000 4470.000000 4467.500000 4464.000000 4460.500000 4457.500000 etc.... Any ideas???? Thanks Ben.

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  • Justifying UIVIews on the iPhone: Algorithm Help

    - by coneybeare
    I have been messing around with a way to justify align a collection of UIView subclasses within a containing view. I am having a little bit of trouble with the algorithm and was hoping someone could help spot my errors. Here is pseudocode of where I am now: // 1 see how many items there are int count = [items count]; // 2 figure out how much white space is left in the containing view float whitespace = [containingView width] - [items totalWidth]; // 3 Figure out the extra left margin to be applied to items[1] through items[count-1] float margin = whitespace/(count-1); // 4 Figure out the size of every subcontainer if it was evenly split float subcontainerWidth = [containingView width]/count; // 5 Apply the margin, starting at the second item for (int i = 1; i < [items count]; i++) { UIView *item = [items objectAtIndex:i]; [item setLeftMargin:(margin + i*subcontainerWidth)]; } The items do not appear to be evenly spaced here. Not even close. Where am I going wrong? Here is a shot of this algorithm in action: EDIT: The code above is pseudocode. I added the actual code here but it might not make sense if you are not familiar with the three20 project. @implementation TTTabStrip (JustifiedBarCategory) - (CGSize)layoutTabs { CGSize size = [super layoutTabs]; CGPoint contentOffset = _scrollView.contentOffset; _scrollView.frame = self.bounds; _scrollView.contentSize = CGSizeMake(size.width + kTabMargin, self.height); CGFloat contentWidth = size.width + kTabMargin; if (contentWidth < _scrollView.size.width) { // do the justify logic // see how many items there are int count = [_tabViews count]; // 2 figure out how much white space is left float whitespace = _scrollView.size.width - contentWidth; // 3 increase the margin on those items somehow to reflect. it should be (whitespace) / count-1 float margin = whitespace/(count-1); // 4 figure out starting point float itemWidth = (_scrollView.size.width-kTabMargin)/count; // apply the margin for (int i = 1; i < [_tabViews count]; i++) { TTTab *tab = [_tabViews objectAtIndex:i]; [tab setLeft:(margin + i*itemWidth)]; } } else { // do the normal, scrollbar logic _scrollView.contentOffset = contentOffset; } return size; } @end

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  • How to use drag and drop within a UIScrollView

    - by user249488
    I am trying to drag and drop UIViews within a UIScrollView. I'd like the UIScrollView to scroll if I drag a UIView so that it intersects the top or bottom of the ScrollView. If it touches the top, it should scroll up. If it touches the bottom, it should scroll down. Once the UIView is moved such that it is no longer intersecting the top or bottom, the scrolling should stop. The first approach I tried was to start an NSTimer whenever I detected that the UIView intersected with the top or bottom of the scrollview. The timer would scroll the UIScrollView bit by bit until it was invalidated. This resulted in very jerky scrolling, since there is no way to predict when the timers will fire. My current approach is to simply scroll all the way to the top or bottom of the ScrollView, like this: [UIView beginAnimations:nil context:NULL]; [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut]; [UIView setAnimationDuration:1.0]; [self.parentScrollview setContentOffset:newOffset animated:NO]; [UIView commitAnimations]; In order to stop scrolling, I try to determine the position of the touch in the touchesMoved: delegate, and use that to calculate the contentOffset to use for the scrollView. The problem is, when I try to get the location in the view via [[touches anyObject] locationInView:self], I get the final end location, rather than the current location. I'm guessing that's because the contentOffset on the scrollView is set immediately. Is there a way to get the actual location of a touch in a situation like this? Or any other way to set the contentOffset when I interrupt the scrolling animation?

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  • Popovercontroller doesn't display full

    - by user2959234
    I have an UIPopovercontroller in with an content that generate from an viewcontroller. popOverController = [[UIPopoverController alloc]initWithPopUp:emLightPopUp]; popOverController.delegate = self; // Get device position. CGRect position = {parentButton.frame.origin,emLightPopUp.popUpView.frame.size}; CGSize popUpViewFrameSize = emLightPopUp.popUpView.frame.size; Link screenshot: http://i.stack.imgur.com/AxqoG.png The issue is that when I change the position of select devices (touched button) upwards, the displayed popup will be resized like the screenshot. I already try to set content size inside the subclass of uipopover but it still doesn't work: self.popoverContentSize = emLightPopUp.popUpView.frame.size; EDIT: I solved this problems by calculate the position that display the popup and scroll the scrollview inside into an upper position. Check out this code: -(void)moveDeviceOutMiddleScreen:(id)deviceButton { UIButton* button = (UIButton*)deviceButton; CGFloat yPositionRange = button.frame.origin.y - self.floorZoomScrollView.contentOffset.y; int middle_top_y = 70; int middle_bottom_y = 166; if (yPositionRange > middle_top_y && yPositionRange < middle_bottom_y) { CGRect newRect = CGRectMake(self.floorZoomScrollView.contentOffset.x, self.floorZoomScrollView.contentOffset.y +yPositionRange*0.6, self.floorZoomScrollView.frame.size.width, self.floorZoomScrollView.frame.size.height); [self.floorZoomScrollView scrollRectToVisible:newRect animated:NO]; } } Thanks for your responses.

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  • Fitting an Image to Screen on Rotation iPhone / iPad ?

    - by user356937
    I have been playing around with one of the iPhone examples from Apple' web site (ScrollViewSuite) . I am trying to tweak it a bit so that when I rotate the the iPad the image will fit into the screen in landscape mode vertical. I have been successful in getting the image to rotate, but the image is larger than the height of the landscape screen, so the bottom is below the screen. I would like to image to scale to the height of the landscape screen. I have been playing around with various autoSizingMask attributes without success. The imageView is called "zoomView" this is the actual image which loads into a scrollView called imageScrollView. I am trying to achieve the screen to rotate and look like this.... olsonvox.com/photos/correct.png However, this is what My screen is looking like. olsonvox.com/photos/incorrect.png I would really appreciate some advice or guidance. Below is the RootViewController.m for the project. Blade # import "RootViewController.h" #define ZOOM_VIEW_TAG 100 #define ZOOM_STEP 1.5 #define THUMB_HEIGHT 150 #define THUMB_V_PADDING 25 #define THUMB_H_PADDING 25 #define CREDIT_LABEL_HEIGHT 25 #define AUTOSCROLL_THRESHOLD 30 @interface RootViewController (ViewHandlingMethods) - (void)toggleThumbView; - (void)pickImageNamed:(NSString *)name; - (NSArray *)imageNames; - (void)createThumbScrollViewIfNecessary; - (void)createSlideUpViewIfNecessary; @end @interface RootViewController (AutoscrollingMethods) - (void)maybeAutoscrollForThumb:(ThumbImageView *)thumb; - (void)autoscrollTimerFired:(NSTimer *)timer; - (void)legalizeAutoscrollDistance; - (float)autoscrollDistanceForProximityToEdge:(float)proximity; @end @interface RootViewController (UtilityMethods) - (CGRect)zoomRectForScale:(float)scale withCenter:(CGPoint)center; @end @implementation RootViewController - (void)loadView { [super loadView]; imageScrollView = [[UIScrollView alloc] initWithFrame:[[self view]bounds]]; // this code makes the image resize to the width and height properly. imageScrollView.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleLeftMargin | UIViewAutoresizingFlexibleRightMargin| UIViewAutoresizingFlexibleBottomMargin| UIViewAutoresizingFlexibleBottomMargin; // TRY SETTNG CENTER HERE SOMEHOW&gt;.... [imageScrollView setBackgroundColor:[UIColor blackColor]]; [imageScrollView setDelegate:self]; [imageScrollView setBouncesZoom:YES]; [[self view] addSubview:imageScrollView]; [self toggleThumbView]; // intitializes with the first image. [self pickImageNamed:@"lookbook1"]; } - (void)dealloc { [imageScrollView release]; [slideUpView release]; [thumbScrollView release]; [super dealloc]; } #pragma mark UIScrollViewDelegate methods - (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView { UIView *view = nil; if (scrollView == imageScrollView) { view = [imageScrollView viewWithTag:ZOOM_VIEW_TAG]; } return view; } /************************************** NOTE **************************************/ /* The following delegate method works around a known bug in zoomToRect:animated: */ /* In the next release after 3.0 this workaround will no longer be necessary */ /**********************************************************************************/ - (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale { [scrollView setZoomScale:scale+0.01 animated:NO]; [scrollView setZoomScale:scale animated:NO]; } #pragma mark TapDetectingImageViewDelegate methods - (void)tapDetectingImageView:(TapDetectingImageView *)view gotSingleTapAtPoint:(CGPoint)tapPoint { // Single tap shows or hides drawer of thumbnails. [self toggleThumbView]; } - (void)tapDetectingImageView:(TapDetectingImageView *)view gotDoubleTapAtPoint:(CGPoint)tapPoint { // double tap zooms in float newScale = [imageScrollView zoomScale] * ZOOM_STEP; CGRect zoomRect = [self zoomRectForScale:newScale withCenter:tapPoint]; [imageScrollView zoomToRect:zoomRect animated:YES]; } - (void)tapDetectingImageView:(TapDetectingImageView *)view gotTwoFingerTapAtPoint:(CGPoint)tapPoint { // two-finger tap zooms out float newScale = [imageScrollView zoomScale] / ZOOM_STEP; CGRect zoomRect = [self zoomRectForScale:newScale withCenter:tapPoint]; [imageScrollView zoomToRect:zoomRect animated:YES]; } #pragma mark ThumbImageViewDelegate methods - (void)thumbImageViewWasTapped:(ThumbImageView *)tiv { [self pickImageNamed:[tiv imageName]]; [self toggleThumbView]; } - (void)thumbImageViewStartedTracking:(ThumbImageView *)tiv { [thumbScrollView bringSubviewToFront:tiv]; } // CONTROLS DRAGGING AND DROPPING THUMBNAILS... - (void)thumbImageViewMoved:(ThumbImageView *)draggingThumb { // check if we've moved close enough to an edge to autoscroll, or far enough away to stop autoscrolling [self maybeAutoscrollForThumb:draggingThumb]; /* The rest of this method handles the reordering of thumbnails in the thumbScrollView. See */ /* ThumbImageView.h and ThumbImageView.m for more information about how this works. */ // we'll reorder only if the thumb is overlapping the scroll view if (CGRectIntersectsRect([draggingThumb frame], [thumbScrollView bounds])) { BOOL draggingRight = [draggingThumb frame].origin.x &gt; [draggingThumb home].origin.x ? YES : NO; /* we're going to shift over all the thumbs who live between the home of the moving thumb */ /* and the current touch location. A thumb counts as living in this area if the midpoint */ /* of its home is contained in the area. */ NSMutableArray *thumbsToShift = [[NSMutableArray alloc] init]; // get the touch location in the coordinate system of the scroll view CGPoint touchLocation = [draggingThumb convertPoint:[draggingThumb touchLocation] toView:thumbScrollView]; // calculate minimum and maximum boundaries of the affected area float minX = draggingRight ? CGRectGetMaxX([draggingThumb home]) : touchLocation.x; float maxX = draggingRight ? touchLocation.x : CGRectGetMinX([draggingThumb home]); // iterate through thumbnails and see which ones need to move over for (ThumbImageView *thumb in [thumbScrollView subviews]) { // skip the thumb being dragged if (thumb == draggingThumb) continue; // skip non-thumb subviews of the scroll view (such as the scroll indicators) if (! [thumb isMemberOfClass:[ThumbImageView class]]) continue; float thumbMidpoint = CGRectGetMidX([thumb home]); if (thumbMidpoint &gt;= minX &amp;&amp; thumbMidpoint &lt;= maxX) { [thumbsToShift addObject:thumb]; } } // shift over the other thumbs to make room for the dragging thumb. (if we're dragging right, they shift to the left) float otherThumbShift = ([draggingThumb home].size.width + THUMB_H_PADDING) * (draggingRight ? -1 : 1); // as we shift over the other thumbs, we'll calculate how much the dragging thumb's home is going to move float draggingThumbShift = 0.0; // send each of the shifting thumbs to its new home for (ThumbImageView *otherThumb in thumbsToShift) { CGRect home = [otherThumb home]; home.origin.x += otherThumbShift; [otherThumb setHome:home]; [otherThumb goHome]; draggingThumbShift += ([otherThumb frame].size.width + THUMB_H_PADDING) * (draggingRight ? 1 : -1); } // change the home of the dragging thumb, but don't send it there because it's still being dragged CGRect home = [draggingThumb home]; home.origin.x += draggingThumbShift; [draggingThumb setHome:home]; } } - (void)thumbImageViewStoppedTracking:(ThumbImageView *)tiv { // if the user lets go of the thumb image view, stop autoscrolling [autoscrollTimer invalidate]; autoscrollTimer = nil; } #pragma mark Autoscrolling methods - (void)maybeAutoscrollForThumb:(ThumbImageView *)thumb { autoscrollDistance = 0; // only autoscroll if the thumb is overlapping the thumbScrollView if (CGRectIntersectsRect([thumb frame], [thumbScrollView bounds])) { CGPoint touchLocation = [thumb convertPoint:[thumb touchLocation] toView:thumbScrollView]; float distanceFromLeftEdge = touchLocation.x - CGRectGetMinX([thumbScrollView bounds]); float distanceFromRightEdge = CGRectGetMaxX([thumbScrollView bounds]) - touchLocation.x; if (distanceFromLeftEdge &lt; AUTOSCROLL_THRESHOLD) { autoscrollDistance = [self autoscrollDistanceForProximityToEdge:distanceFromLeftEdge] * -1; // if scrolling left, distance is negative } else if (distanceFromRightEdge &lt; AUTOSCROLL_THRESHOLD) { autoscrollDistance = [self autoscrollDistanceForProximityToEdge:distanceFromRightEdge]; } } // if no autoscrolling, stop and clear timer if (autoscrollDistance == 0) { [autoscrollTimer invalidate]; autoscrollTimer = nil; } // otherwise create and start timer (if we don't already have a timer going) else if (autoscrollTimer == nil) { autoscrollTimer = [NSTimer scheduledTimerWithTimeInterval:(1.0 / 60.0) target:self selector:@selector(autoscrollTimerFired:) userInfo:thumb repeats:YES]; } } - (float)autoscrollDistanceForProximityToEdge:(float)proximity { // the scroll distance grows as the proximity to the edge decreases, so that moving the thumb // further over results in faster scrolling. return ceilf((AUTOSCROLL_THRESHOLD - proximity) / 5.0); } - (void)legalizeAutoscrollDistance { // makes sure the autoscroll distance won't result in scrolling past the content of the scroll view float minimumLegalDistance = [thumbScrollView contentOffset].x * -1; float maximumLegalDistance = [thumbScrollView contentSize].width - ([thumbScrollView frame].size.width + [thumbScrollView contentOffset].x); autoscrollDistance = MAX(autoscrollDistance, minimumLegalDistance); autoscrollDistance = MIN(autoscrollDistance, maximumLegalDistance); } - (void)autoscrollTimerFired:(NSTimer*)timer { [self legalizeAutoscrollDistance]; // autoscroll by changing content offset CGPoint contentOffset = [thumbScrollView contentOffset]; contentOffset.x += autoscrollDistance; [thumbScrollView setContentOffset:contentOffset]; // adjust thumb position so it appears to stay still ThumbImageView *thumb = (ThumbImageView *)[timer userInfo]; [thumb moveByOffset:CGPointMake(autoscrollDistance, 0)]; } #pragma mark View handling methods - (void)toggleThumbView { [self createSlideUpViewIfNecessary]; // no-op if slideUpView has already been created CGRect frame = [slideUpView frame]; if (thumbViewShowing) { frame.origin.y = 0; } else { frame.origin.y = -225; } [UIView beginAnimations:nil context:nil]; [UIView setAnimationDuration:0.3]; [slideUpView setFrame:frame]; [UIView commitAnimations]; thumbViewShowing = !thumbViewShowing; } - (void)pickImageNamed:(NSString *)name { // first remove previous image view, if any [[imageScrollView viewWithTag:ZOOM_VIEW_TAG] removeFromSuperview]; UIImage *image = [UIImage imageNamed:[NSString stringWithFormat:@"%@.jpg", name]]; TapDetectingImageView *zoomView = [[TapDetectingImageView alloc] initWithImage:image]; zoomView.autoresizingMask = UIViewAutoresizingFlexibleWidth ; [zoomView setDelegate:self]; [zoomView setTag:ZOOM_VIEW_TAG]; [imageScrollView addSubview:zoomView]; [imageScrollView setContentSize:[zoomView frame].size]; [zoomView release]; // choose minimum scale so image width fits screen float minScale = [imageScrollView frame].size.width / [zoomView frame].size.width; [imageScrollView setMinimumZoomScale:minScale]; [imageScrollView setZoomScale:minScale]; [imageScrollView setContentOffset:CGPointZero]; } - (NSArray *)imageNames { // the filenames are stored in a plist in the app bundle, so create array by reading this plist NSString *path = [[NSBundle mainBundle] pathForResource:@"Images" ofType:@"plist"]; NSData *plistData = [NSData dataWithContentsOfFile:path]; NSString *error; NSPropertyListFormat format; NSArray *imageNames = [NSPropertyListSerialization propertyListFromData:plistData mutabilityOption:NSPropertyListImmutable format:&amp;format errorDescription:&amp;error]; if (!imageNames) { NSLog(@"Failed to read image names. Error: %@", error); [error release]; } return imageNames; } - (void)createSlideUpViewIfNecessary { if (!slideUpView) { [self createThumbScrollViewIfNecessary]; CGRect bounds = [[self view] bounds]; float thumbHeight = [thumbScrollView frame].size.height; float labelHeight = CREDIT_LABEL_HEIGHT; // create label giving credit for images UILabel *creditLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, thumbHeight, bounds.size.width, labelHeight)]; [creditLabel setBackgroundColor:[UIColor clearColor]]; [creditLabel setTextColor:[UIColor whiteColor]]; // [creditLabel setFont:[UIFont fontWithName:@"Helvetica" size:16]]; // [creditLabel setText:@"SAMPLE TEXT"]; [creditLabel setTextAlignment:UITextAlignmentCenter]; // create container view that will hold scroll view and label CGRect frame = CGRectMake(0.0, -225.00, bounds.size.width+256, thumbHeight + labelHeight); slideUpView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleTopMargin; slideUpView = [[UIView alloc] initWithFrame:frame]; [slideUpView setBackgroundColor:[UIColor blackColor]]; [slideUpView setOpaque:NO]; [slideUpView setAlpha:.75]; [[self view] addSubview:slideUpView]; // add subviews to container view [slideUpView addSubview:thumbScrollView]; [slideUpView addSubview:creditLabel]; [creditLabel release]; } } - (void)createThumbScrollViewIfNecessary { if (!thumbScrollView) { float scrollViewHeight = THUMB_HEIGHT + THUMB_V_PADDING; float scrollViewWidth = [[self view] bounds].size.width; thumbScrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, scrollViewWidth, scrollViewHeight)]; [thumbScrollView setCanCancelContentTouches:NO]; [thumbScrollView setClipsToBounds:NO]; // now place all the thumb views as subviews of the scroll view // and in the course of doing so calculate the content width float xPosition = THUMB_H_PADDING; for (NSString *name in [self imageNames]) { UIImage *thumbImage = [UIImage imageNamed:[NSString stringWithFormat:@"%@_thumb.jpg", name]]; if (thumbImage) { ThumbImageView *thumbView = [[ThumbImageView alloc] initWithImage:thumbImage]; [thumbView setDelegate:self]; [thumbView setImageName:name]; CGRect frame = [thumbView frame]; frame.origin.y = THUMB_V_PADDING; frame.origin.x = xPosition; [thumbView setFrame:frame]; [thumbView setHome:frame]; [thumbScrollView addSubview:thumbView]; [thumbView release]; xPosition += (frame.size.width + THUMB_H_PADDING); } } [thumbScrollView setContentSize:CGSizeMake(xPosition, scrollViewHeight)]; } } #pragma mark Utility methods - (CGRect)zoomRectForScale:(float)scale withCenter:(CGPoint)center { CGRect zoomRect; // the zoom rect is in the content view's coordinates. // At a zoom scale of 1.0, it would be the size of the imageScrollView's bounds. // As the zoom scale decreases, so more content is visible, the size of the rect grows. zoomRect.size.height = [imageScrollView frame].size.height / scale; zoomRect.size.width = [imageScrollView frame].size.width / scale; // choose an origin so as to get the right center. zoomRect.origin.x = center.x - (zoomRect.size.width / 2.0); zoomRect.origin.y = center.y - (zoomRect.size.height / 2.0); return zoomRect; } #pragma mark - #pragma mark Rotation support // Ensure that the view controller supports rotation and that the split view can therefore show in both portrait and landscape. - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { return YES; } @end

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  • iPhone SDK: How to centre content in a UIScrollView during setZoomScale?

    - by Russell Quinn
    I'm using a UIScrollView to show photos. If they are zoomed out so they are smaller than the scroll view in one dimension then the content is centred using contentInset and contentOffset. This all works fine for scrolling and manual zooming. However, if I use setZoomScale (with animated YES) then when zooming out the scroll view sets the top left edge to 0,0 during the animation and then snaps it back afterwards. It seems like the zoom animation ignores the contentInset and contentOffset settings. Does anyone have any idea how to overcome this problem? Thanks, Russell.

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  • iPhone UIScrollView / setContentOffset weirdness

    - by bibac
    Hi, I have a weird issue with setContentOffset which I don't seem to be able to solve: I'm trying to build an "endless" scroll view, so I'd like to reset the content offset at a certain position. With the code below setContentOffset will be called at x=160px. If I drag the scroll view my log looks like this: offset: 158 offset: 159 offset: 160 offset: 80 offset: 160 What happens is that my setContentOffset (to 80) is performed, when I keep on dragging UIScrollView seem to have forgotten about it and continues at 160. Even weirder: When I set animated:YES it works. Maybe a timing issue? When I call setContentOffset from within scrollViewDidScroll, scrollViewDidScroll will be called again. - (void)scrollViewDidScroll:(UIScrollView *)scrollView { NSInteger tileNo = floor(scrollView.contentOffset.x / 80); NSLog(@"offset: %f, tile: %d, lastTile: %d", scrollView.contentOffset.x, tileNo, lastTileNo); if (tileNo > lastTileNo) { [scrollView setContentOffset:CGPointMake(80, 0) animated:NO]; } lastTileNo = tileNo; } Thanks for helping me out, Stephan

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  • How much difference you find between scrollview offset and contentview offset of table?

    - by neha
    Hi all, In my application, I want to detect the end of the entire table with scrollview. Since there're no sections in my scrollview, I'm using noOfRows*rowHeight to reach the end. I'm using scrollview.contentOffset.y to detect the y offset, but this contentOffset isn't matching the multiplication result i.e. I have 20 rows and with height as 250. So it comes as 5000, but my scrollview.offset.y at the end of last cell is nearly about 4650. What's this difference? Thanx in advance.

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  • How do I properly handle rotation of a UIScrollView containing UIImageViews?

    - by bpapa
    I'm developing an image viewer, much like the Photos App. It's a UIScrollView with paging enabled with images loaded from the internet, so I've adapted portions of the LazyTableImages sample. The Scroll View and each ImageView inside of it have all of their autoresize mask flags set. When I first observed how resizes were happening during rotation, it looked good, but once I started trying to interact with the scroll view, I realized that I also had to programmatically change the size of the contentView. I did that by implementing didRotateFromInterfaceOrientation: in my view controller. [self.scrollView setContentSize:CGSizeMake(numberOfImages * portraitWidth, [scrollView bounds].size.height)]; With interaction behaving properly, I then discovered that, if I was viewing the second photo and rotated, portions of both the 1st and 2nd photos would be shown on the screen. I needed to change the contentOffset as well. I've tried to fix this two ways - both by using the scrollRectToVisible:animated: method of UIScrollView, as well as trying to set the contentOffset property directly. And I've experimented by putting this code in implementations of both the "one-step" and "two-step" responses to changes in Orientation. For example: -(void)didAnimateFirstHalfOfRotationToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation { [self.scrollView setContentOffset:CGPointMake(currentlyViewedPhotoIndex * largeImageHeight,0) animated:YES]; In all cases though, it just looks janky as hell. Either I clearly see the scroll happen, or it just jumps. Uuuuuuuuuuugly! Is there a way to do this so that it behaves exactly like the Photos app does?

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  • Redrawing content of UIWebView

    - by btate
    I have a bunch of webviews with static html content that I'm putting in a scroll view as pages. That works fine, but having 20 something full screen subviews of the scroll view is causing some lag. I solved that by only placing 5 at a time in there. The current view, and the two next and two previous. The problem now is that any web view that is not a subview of the scroll view is not drawing correctly based on the device orientation. The frame of the webview is printing out correct, but the actual content is drawing in portrait mode. So there is essentially a strip of blank space to the right of the content. How do I go about re rendering the content without reloading the page? Here's the relevant code: - (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation) fromInterfaceOrientation{ [self resizeSubViews]; } - (void) setupWebViews{ if(_webViews == nil) _webViews = [[NSMutableArray alloc] init]; // This is where the navigation would come into play as far as loading up available web views [_webViews removeAllObjects]; // for loop here to create web views for (int i = 0; i < 20; i++) { //CDCWebViewController *webView = [[[MyInternalWebView alloc] initWithFrame:_webViewWrapper.frame] retain]; MyInternalWebView *page = [[[MyInternalWebView alloc] init] retain]; [page loadRequest:[NSURLRequest requestWithURL:_url]]; [page setCdcIWVdelegate:self]; [page setTestIndex:i]; [page setPageIndex:i]; [_webViews addObject:page]; [self loadScrollViewWithPage:i]; } [self clearUnusedWebViews:_pageControl.currentPage]; } - (void) setupWebViewWrapper{ // a page is the width of the scroll view _webViewWrapper.pagingEnabled = YES; _pageControl = [[[UIPageControl alloc] init] retain]; _webViewWrapper.showsHorizontalScrollIndicator = NO; _webViewWrapper.showsVerticalScrollIndicator = NO; _webViewWrapper.scrollsToTop = NO; _webViewWrapper.delegate = self; _pageControl.numberOfPages = [_webViews count]; _pageControl.currentPage = 0; } - (void) resizeSubViews{ // The frame is set in IB _webViewWrapper.contentSize = CGSizeMake(_webViewWrapper.frame.size.width * [_webViews count], _webViewWrapper.frame.size.height); // Move the content offset. _webViewWrapper.contentOffset = CGPointMake(_webViewWrapper.frame.size.width * _pageControl.currentPage, _webViewWrapper.contentOffset.y); for (MyInternalWebView *subview in _webViewWrapper.subviews) { // Reset the frame height and width here? CGRect frame = _webViewWrapper.frame; frame.origin.x = frame.size.width * subview.pageIndex; frame.origin.y = 0; [subview setFrame:frame]; } } //***************************************************** //* //* ScrollView Functions //* //***************************************************** - (void)loadScrollViewWithPage:(int)page { // Make sure we're not out of bounds if (page < 0) return; if (page >= [_webViews count]) return; MyInternalWebView *webView = [_webViews objectAtIndex:page]; // Add the preloaded webview to the scrollview if it's not there already if (nil == [webView superview]) { CGRect frame = _webViewWrapper.frame; //NSLog(@"width = %f", frame.size.width); frame.origin.x = frame.size.width * page; frame.origin.y = 0; //NSLog(@"setting frame for page %d %@", page, NSStringFromCGRect(frame)); [webView setFrame:frame]; [_webViewWrapper addSubview:[_webViews objectAtIndex:page]]; // Now that the new one is loaded, clear what doesn't need to be here [self clearUnusedWebViews:page]; } } - (void) clearUnusedWebViews: (NSInteger) page{ for (int i = 0; i < [_webViews count]; i++) { if ((page - i) <= 2 && i - page <= 2) { continue; } [[_webViews objectAtIndex:i] removeFromSuperview]; } } - (void)scrollViewDidScroll:(UIScrollView *)sender { // Switch the indicator when more than 50% of the previous/next page is visible CGFloat pageWidth = _webViewWrapper.frame.size.width; NSInteger page = floor((_webViewWrapper.contentOffset.x - pageWidth / 2) / pageWidth) + 1; _pageControl.currentPage = page; // load the visible page and the page on either side of it (to avoid flashes when the user starts scrolling) [self loadScrollViewWithPage:page - 2]; [self loadScrollViewWithPage:page - 1]; [self loadScrollViewWithPage:page]; [self loadScrollViewWithPage:page + 1]; [self loadScrollViewWithPage:page + 2]; }

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  • UITableView having one Cell with multiple UITextFields (some of them in one row) scrolling crazy

    - by Allisone
    I have a UITableView (grouped). In that tableview I have several UITableViewCells, some custom with nib, some default. One Cell (custom) with nib has several UITextfields for address information, thus also one row has zip-code and city in one row. When I get the keyboard the tableview size seems to be adjusted automatically (vs. another viewController in the app with just a scrollview where I had to code this functionality on my own) so that i can scroll to the bottom of my tableview (and see it) even though the keyboard is up. That's good. BUT when I click on a textfield the tableview gets either scrolled up, or down, I can't figure out the logic. It seems to be rather random up/down scrolling / contentOffset setting. So I have bound the Editing Did Begin events of the textfields to a function that has this code. - (IBAction)textFieldDidBeginEditing:(UITextField *)textField { CGPoint pt; CGRect rc = [textField bounds]; rc = [textField convertRect:rc toView:self.tableView]; pt = rc.origin; pt.x = 0; [self.tableView setContentOffset:pt animated:YES]; ... } This, well, it seems to work most of the time, BUT it doesn't work if I click the first textfield (the view jumps so that the second row gets to the top and the first row is out of the current visible view frame) AND it also doesn't work if I first select the zip textfield and next the city textfield (both in one row) or vice versa. If I do so, the tableview seems to jump to the (grouped tableview) top of my viewForHeaderInSection(this section with this mentioned cell with all my textfields) What is is going on ? Why is this happening ? How to fix this ? Edit This on the other hand behaves as expected (for the two Textviews wit same origin.y) if (self.tableView.contentOffset.y == pt.y) { pt.y = pt.y + 1; [self.tableView setContentOffset:pt animated:YES]; }else { [self.tableView setContentOffset:pt animated:YES]; } But this is a stupid solution. I wouldn't like to keep it that way. And this also doesn't fix the wrong jumping, when clicking the first textfield at first.

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  • iPhone scrollView won't scroll after keyboard is closed

    - by Rob
    I was trying to implement a way to have the UITextField move up when the keyboard opened so that the user could see what they were typing but after implementing the code - it locks my scroll. The view will scroll when the user first gets to that view but after inputting text and closing the keyboard it locks the view. I suspect that it is a problem somewhere in this code: - (void) viewWillAppear:(BOOL)animated { [super viewWillAppear:animated]; NSLog(@"Registering for keyboard events"); // Register for the events [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector (keyboardDidShow:) name: UIKeyboardDidShowNotification object:nil]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector (keyboardDidHide:) name: UIKeyboardDidHideNotification object:nil]; // Setup content size scrollView.contentSize = CGSizeMake(SCROLLVIEW_CONTENT_WIDTH, SCROLLVIEW_CONTENT_HEIGHT); //Initially the keyboard is hidden keyboardVisible = NO; } -(void) viewWillDisappear:(BOOL)animated { NSLog (@"Unregister for keyboard events"); [[NSNotificationCenter defaultCenter] removeObserver:self]; } //**-------------------------------** - (void) keyboardDidShow: (NSNotification *)notif { NSLog(@"Keyboard is visible"); // If keyboard is visible, return if (keyboardVisible) { NSLog(@"Keyboard is already visible. Ignore notification."); return; } // Get the size of the keyboard. NSDictionary* info = [notif userInfo]; NSValue* aValue = [info objectForKey:UIKeyboardBoundsUserInfoKey]; CGSize keyboardSize = [aValue CGRectValue].size; // Save the current location so we can restore // when keyboard is dismissed offset = scrollView.contentOffset; // Resize the scroll view to make room for the keyboard CGRect viewFrame = scrollView.frame; viewFrame.size.height -= keyboardSize.height; scrollView.frame = viewFrame; CGRect textFieldRect = [activeField frame]; textFieldRect.origin.y += 10; [scrollView scrollRectToVisible:textFieldRect animated:YES]; NSLog(@"ao fim"); // Keyboard is now visible keyboardVisible = YES; } -(void) keyboardDidHide: (NSNotification *)notif { // Is the keyboard already shown if (!keyboardVisible) { NSLog(@"Keyboard is already hidden. Ignore notification."); return; } // Reset the frame scroll view to its original value scrollView.frame = CGRectMake(0, 0, SCROLLVIEW_CONTENT_WIDTH, SCROLLVIEW_CONTENT_HEIGHT); // Reset the scrollview to previous location scrollView.contentOffset = offset; // Keyboard is no longer visible keyboardVisible = NO; } -(BOOL) textFieldShouldBeginEditing:(UITextField*)textField { activeField = textField; return YES; } I defined the size above the #imports as: #define SCROLLVIEW_CONTENT_HEIGHT 1000 #define SCROLLVIEW_CONTENT_WIDTH 320 Really not sure what the issue is.

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  • MIN() and MAX() in Swift and converting Int to CGFloat

    - by gotnull
    I'm getting some errors with the following methods: 1) How do I return screenHeight / cellCount as a CGFLoat for the first method? 2) How do I use the equivalent of ObjC's MIN() and MAX() in the second method? func tableView(tableView: UITableView!, heightForRowAtIndexPath indexPath: NSIndexPath!) -> CGFloat { var cellCount = Int(self.tableView.numberOfRowsInSection(indexPath.section)) return screenHeight / cellCount as CGFloat } // #pragma mark - UIScrollViewDelegate func scrollViewDidScroll(scrollView: UIScrollView) { let height = CGFloat(scrollView.bounds.size.height) let position = CGFloat(MAX(scrollView.contentOffset.y, 0.0)) let percent = CGFloat(MIN(position / height, 1.0)) blurredImageView.alpha = percent }

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  • UIScrollView setZoomScale not working ?

    - by iFloh
    Hi, I am struggeling with my UIScrollview to get it to zoom-in the underlying UIImageView. In my view controller I set - (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView { return myImageView; } In the viewDidLoad method I try to set the zoomScale to 2 as follows (note the UIImageView and Image is set in Interface Builder): - (void)viewDidLoad { [super viewDidLoad]; myScrollView.contentSize = CGSizeMake(myImageView.frame.size.width, myImageView.frame.size.height); myScrollView.contentOffset = CGPointMake(941.0, 990.0); myScrollView.minimumZoomScale = 0.1; myScrollView.maximumZoomScale = 10.0; myScrollView.zoomScale = 0.7; myScrollView.clipsToBounds = YES; myScrollView.delegate = self; NSLog(@"zoomScale: %.1f, minZoolScale: %.3f", myScrollView.zoomScale, myScrollView.minimumZoomScale); } I tried a few variations of this, but the NSLog always shows a zoomScale of 1.0. Any ideas where I screw this one up?

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  • UIScrollview setContentOffset immediate animation?

    - by Jess
    Is there anyway to get the setContentOffset animation to happen immediately instead of waiting until the app returns to the main run loop? I tried setting the animation property to NO and nesting inside of an animation block but it still waits until returning to the main run loop. I've also tried using a sub method to perform the animation. My problem is I perform some heavy work after setting the contentOffset so the scroll view waits until this work is complete to animate the setting of the content offset so it appears to lag for a second.

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  • Intercept UITableView scroll touches

    - by Jonesy
    Is it possible to control when the UITableView scrolls in my own code. I am trying to get behaviour where a vertical swipe scrolls and a horizontal swipe gets passed through to my code (of which there are many example) BUT I want a DIAGONAL swipe to do nothing, i.e the UITableView should not even begin scrolling. I tried catching it in here - (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView but the scrollView.contentOffset.x is always 0 so I cannot detect a horizontal movement. I also tried subclassing UITableView and implementing - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event - (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event etc.. but the UITableView (and I guess it's parent UIScrollView) start to scroll before the touches are notified? To re-iterate, I want the UITableView scrolling to be locked if a diagonal swipe is made, but to scroll vertically normally. (This behaviour can be seen in Tweetie(Twitter) for the iPhone) Thanks for any help!

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  • iPhone UIScrollView - How to animate scrolling with steady contents?

    - by timbos
    Hi all, I'm wondering if anyone knows how to prevent the contents of a uiscrollview from moving unsteadily when scrolling manually by setting the content offset. When scrolling by touch the text remains clear and steady. I would like to recreate this by animating with the animated option set to false. I'm using a timer to scroll at a given interval. The text is being drawn to a view in the contents, but it vibrates and it becomes more difficult to read clearly when animating at a greater speed. The speed varies and the scrolling must respond to changes in speed quickly. Here's some code - - (void) scrollIncrAmt:(float) amt { _currentSpeedIncr = amt; NSArray* arr = [SharedTickerInfo sharedTickerInfo].sDataArray; DataObj* tdObj = [arr objectAtIndex:_row]; if ( ![tdObj isDirLeft] ) { amt = -amt; } float scrollTo = self.scrollView.contentOffset.x + amt; [scrollView setContentOffset:CGPointMake(scrollTo, 0.0f) animated:NO]; }

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