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Search found 236 results on 10 pages for 'mystify'.

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  • Can I safely store UInt32 to NSUInteger?

    - by mystify
    In the header, it is defined like: #if __LP64__ || (TARGET_OS_EMBEDDED && !TARGET_OS_IPHONE) || TARGET_OS_WIN32 || NS_BUILD_32_LIKE_64 typedef long NSInteger; typedef unsigned long NSUInteger; #else typedef int NSInteger; typedef unsigned int NSUInteger; #endif So does an UInt32 fit without problems into an NSUInteger (an unsigned int)? Where's the difference between UInt32 and unsigned int? And I assume that an unsigned long is bigger than an unsigned int?

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  • How to create a formatted localized string?

    - by mystify
    I have a localized string which needs to take a few variables. However, in localization it is important that the order of the variables can change from language to language. So this is not a good idea: NSString *text = NSLocalizedString(@"My birthday is at %@ %@ in %@", nil); In some languages some words come before others, while in others it's reverse. I lack of an good example at the moment. How would I provide NAMED variables in a formatted string? Is there any way to do it without some heavy self-made string replacements? Even some numbered variables like {%@1}, {%@2}, and so on would be sufficient... is there a solution?

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  • How to increment a value using a C-Preprocessor in Objective-C?

    - by mystify
    Example: I try to do this: static NSInteger stepNum = 1; #define METHODNAME(i) -(void)step##i #define STEP METHODNAME(stepNum++) @implementation Test STEP { // do stuff... [self nextFrame:@selector(step2) afterDelay:1]; } STEP { // do stuff... [self nextFrame:@selector(step3) afterDelay:1]; } STEP { // do stuff... [self nextFrame:@selector(step4) afterDelay:1]; } // ... When building, Xcode complains that it can't increment stepNum. This seems logical to me, because at this time the code is not "alive" and this pre-processing substitution stuff happens before actually compiling the source code. Is there another way I could have an variable be incremented on every usage of STEP macro, the easy way?

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  • How to track the touch vector?

    - by mystify
    I need to calculate the direction of dragging a touch, to determine if the user is dragging up the screen, or down the screen. Actually pretty simple, right? But: 1) Finger goes down, you get -touchesBegan:withEvent: called 2) Must wait until finger moves, and -touchesMoved:withEvent: gets called 3) Problem: At this point it's dangerous to tell if the user did drag up or down. My thoughts: Check the time and accumulate calculates vectors until it's secure to tell the direction of touch. Easy? No. Think about it: What if the user holds the finger down for 5 minutes on the same spot, but THEN decides to move up or down? BANG! Your code would fail, because it tried to determine the direction of touch when the finger didn't move really. Problem 2: When the finger goes down and stays at the same spot for a few seconds because the user is a bit in the wind and thinks about what to do now, you'll get a lot of -touchesMoved:withEvent: calls very likely, but with very minor changes in touch location. So my next thought: Do the accumulation in -touchesMoved:withEvent:, but only if a certain threshold of movement has been exceeded. I bet you have some better concepts in place?

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  • How to make a table view which can be scrolled for ever?

    - by mystify
    I have a set of 100 rows, pretty similar to values which can be selected in a picker. When the user scrolls the table, I want the rows to be appended like an forever-ongoing assembly-belt. So when the user scrolls down and reaches the row 100, and scrolls even further, the table view will show again row 1, and so on. Reverse direction same thing. My thoughts: don't display scroll indicators (they would make not much sense, probably) what value to return in the numberOfRows delegate method? This infinity constant? in cellForRowAtIndexPath: simply wrap the index around when it exceeds bounds?

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  • What's void *userData exactly?

    - by mystify
    In a C function declaration, I have seen this parameter definition: void *userData so, what exactly is that? My guess: the void says it can be anything arbitrary, or even nothing. Almost similar to id of objective-c. It just allows to pass in whatever data structure you like. The star in front of userData says, that the argument must be passed in by reference. So when using this stuff in the function body, typically it must be casted and dereferenced. So if I pass in an pointer to SomeClass instance, I would get that like this: SomeClass *myObj = (SomeClass*)userData; In the case I had nothing special to pass along, I would provide NULL as argument. Are my assumptions correct? Or did I get something wrong?

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  • How to animate stuff when using -drawRect: ?

    - by mystify
    I didn't use subviews but painted my things with -drawRect: inside an UIView subclass. Now I want to do some animations in there. I guess that I can't count on core animation now since I have no subviews. So how would I animate then? Would I set up a timer which fires like 30 times per second? How would I know the animation step? Would I make an ivar which counts the frame of the animation so that I can do my stuff in -drawRect as it gets called?

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  • If I create a transient property in the model, isn't this managed by core data then?

    - by mystify
    Just to grok this: If I had a transient property, lets say averagePrice, and I mark that as "transient" in the data modeler: This will not be persistet, and no column will be created in SQLite for that? And: If I make my own NSManagedObject subclass with an averagePrice property, does it make any sense to model that property in the xcdatamodel file? Would it make a difference if I would simply create a property in my subclass and not model that in the entity? (I think: yes, it doesn't matter at all ... but not sure)

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  • How to draw an CGImage with some alpha transparency?

    - by mystify
    Want to draw an UIImageView which has an CGImage, and the UIImageView has alpha 0.5f. But this CGContextDrawImage function doesnt take an transparency value. So how could I draw an image slightly transparent? To be clear: The image itself is not transparent, but I want it to be "dimmed" a little bit. Just like you would do with an UIImageView and some alpha like 0.5f :-)

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  • What is this line doing exactly?

    - by mystify
    From the Finch audio library: - (void) play { [[sounds objectAtIndex:current] play]; current = (current + 1) % [sounds count]; // this line here... } I try to grok it: There is a number of sounds n, and current is increased by 1 on every iteration. As soon as current is bigger than number of sounds n, the modulo returns zero. That way, it starts from the beginning. Is this correct?

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  • Why does UITableViewCell have a contentView property?

    - by mystify
    What's the point of this contentView property? I mean: Why aren't all the subviews just added to self? Let me get that right: Every cell is a view (UITabvleViewCell is a UIView subclass). And this fat view has another fat view with same bounds sitting on top of it, called contentView. That contentView then carries all those other subviews. Now why didn't they save that extra chunk of memory? Is there any genius logic behind this decision? Would love to understand the reason for this.

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  • Is Core Animation causing my subviews to call -drawRect for every single frame?

    - by mystify
    I made a nice UIView subclass which paints all its stuff in -drawRect:, because people said that's good. That view is a subview of another. This another view is beeing animated with Core Animation: It's scaled down, rotated and moved. However, I encountered this: -drawRect seems to get called trillion of times during animation, and performance sucks. Is that normal or did I do something wrong, probably?

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  • Why are all my masked views unmasked in my view snapshot?

    - by mystify
    I'm taking a snapshot of an view. This view has got some subviews which have layer masks applied to them. For some reason, those masks take no effect in the snapshot and the masked parts are completely visible. UIGraphicsBeginImageContext(theView.frame.size); [theView.layer renderInContext:UIGraphicsGetCurrentContext()]; UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); I assume this is a bug in the framework. But maybe it's not? Did I do anything wrong here?

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  • Is there any reason why someone would want to create an Core Data model programmatically?

    - by mystify
    I wonder in which cases it would be good to make an NSManagedObjectModel completely programmatically, with NSEntityDescription instances and all this stuff. I'm that kind of person who prefers to code programmatically, rejecting Interface Builder. But when it comes to Core Data, I have a hard time figuring out why I should kill my time NOT using the nice Xcode Data Modeler tool. And since data models are stuck to a given state (except when you want to do some ugly migration operations where thinks probably go wrong and users get mad, really mad), I see no big sense in a data model that's made programmatically for the purpose of changing it all the time. Did I miss something?

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  • Does it make a difference in performance if I use self.fooBar instead of fooBar?

    - by mystify
    Note: I know exactly what a property is. This question is about performance. Using self.fooBar for READ access seems a waste of time for me. Unnecessary Objective-C messaging is going on. The getters typically simply pass along the ivar, so as long as it's pretty sure there will be no reasonable getter method written, I think it's perfectly fine to bypass this heavy guy. Objective-C messaging is about 20 times slower than direct calls. So if there is some high-performance-high-frequency code with hundreds of properties in use, maybe it does help a lot to avoid unnessessary objective-c messaging? Or am I wasting my time thinking about this?

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  • Does UIScrollView have a special content view for making the scrolling possible?

    - by mystify
    I wonder if UIScrollView has got an "hidden" subview acting as an container for the content. If I scroll a scroll view, is that content view moved up/down in the scroll view? Or is the scrolling offset applied to the bounds of that UIScrollView instance? Or: Does UIScrollView use an additional view as container, or is all content added directly to the view? The documentation doesn't tell much about wether it has a content container or not.

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