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  • Can't get Jacobi algorithm to work in Objective-C

    - by Chris Long
    Hi, For some reason, I can't get this program to work. I've had other CS majors look at it and they can't figure it out either. This program performs the Jacobi algorithm (you can see step-by-step instructions and a MATLAB implementation here). BTW, it's different from the Wikipedia article of the same name. Since NSArray is one-dimensional, I added a method that makes it act like a two-dimensional C array. After running the Jacobi algorithm many times, the diagonal entries in the NSArray (i[0][0], i[1][1], etc.) are supposed to get bigger and the others approach 0. For some reason though, they all increase exponentially. For instance, i[2][4] should equal 0.0000009, not 9999999, while i[2][2] should be big. Thanks in advance, Chris NSArray+Matrix.m @implementation NSArray (Matrix) @dynamic offValue, transposed; - (double)offValue { double sum = 0.0; for ( MatrixItem *item in self ) if ( item.nonDiagonal ) sum += pow( item.value, 2.0 ); return sum; } - (NSMutableArray *)transposed { NSMutableArray *transpose = [[[NSMutableArray alloc] init] autorelease]; int i, j; for ( i = 0; i < 5; i++ ) { for ( j = 0; j < 5; j++ ) { [transpose addObject:[self objectAtRow:j andColumn:i]]; } } return transpose; } - (id)objectAtRow:(NSUInteger)row andColumn:(NSUInteger)column { NSUInteger index = 5 * row + column; return [self objectAtIndex:index]; } - (NSMutableArray *)multiplyWithMatrix:(NSArray *)array { NSMutableArray *result = [[NSMutableArray alloc] init]; int i = 0, j = 0, k = 0; double value; for ( i = 0; i < 5; i++ ) { value = 0.0; for ( j = 0; j < 5; j++ ) { for ( k = 0; k < 5; k++ ) { MatrixItem *firstItem = [self objectAtRow:i andColumn:k]; MatrixItem *secondItem = [array objectAtRow:k andColumn:j]; value += firstItem.value * secondItem.value; } MatrixItem *item = [[MatrixItem alloc] initWithValue:value]; item.row = i; item.column = j; [result addObject:item]; } } return result; } @end Jacobi_AlgorithmAppDelegate.m // ... - (void)jacobiAlgorithmWithEntry:(MatrixItem *)entry { MatrixItem *b11 = [matrix objectAtRow:entry.row andColumn:entry.row]; MatrixItem *b22 = [matrix objectAtRow:entry.column andColumn:entry.column]; double muPlus = ( b22.value + b11.value ) / 2.0; muPlus += sqrt( pow((b22.value - b11.value), 2.0) + 4.0 * pow(entry.value, 2.0) ); Vector *u1 = [[[Vector alloc] initWithX:(-1.0 * entry.value) andY:(b11.value - muPlus)] autorelease]; [u1 normalize]; Vector *u2 = [[[Vector alloc] initWithX:-u1.y andY:u1.x] autorelease]; NSMutableArray *g = [[[NSMutableArray alloc] init] autorelease]; for ( int i = 0; i <= 24; i++ ) { MatrixItem *item = [[[MatrixItem alloc] init] autorelease]; if ( i == 6*entry.row ) item.value = u1.x; else if ( i == 6*entry.column ) item.value = u2.y; else if ( i == ( 5*entry.row + entry.column ) || i == ( 5*entry.column + entry.row ) ) item.value = u1.y; else if ( i % 6 == 0 ) item.value = 1.0; else item.value = 0.0; [g addObject:item]; } NSMutableArray *firstResult = [[g.transposed multiplyWithMatrix:matrix] autorelease]; matrix = [firstResult multiplyWithMatrix:g]; } // ...

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  • Any way to ask a method for its name?

    - by Andy
    I'm trying to debug an iPhone app I'm working on, and the idea of adding fifty NSLog statements to the various source files gives me the willies. What I'd like to do is write a pair of statements, say NSString *methodName = [self methodName]; NSLog(@"%@", methodName); that I can just paste into each method I need to. Is there a way to do this? Is there some Objective-C construct for asking a method for its name? Or am I gonna have to do this the hard way?

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  • Retrieving a unique result set with Core Data

    - by randombits
    I have a core data based app that manages a bunch of entities. I'm looking to be able to do the following. I have an entity "SomeEntity" with the attributes: name, type, rank, foo1, foo2. Now, SomeEntity has several rows if when we're speaking strictly in SQL terms. What I'm trying to accomplish is to retrieve only available types, even though each instance can have duplicate types. I also need them returned in order according to rank. So in SQL, what I'm looking for is the following: SELECT DISTINCT(type) ORDER BY rank ASC Here is the code I have so far that's breaking: NSError *error = NULL; NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; [fetchRequest setReturnsDistinctResults:YES]; [fetchRequest setPropertiesToFetch:[NSArray arrayWithObjects:@"type", @"rank", nil]]; NSEntityDescription *entity = [NSEntityDescription entityForName:@"SomeEntity" inManagedObjectContext:managedObjectContext]; [fetchRequest setEntity:entity]; // sort by rank NSSortDescriptor *rankDescriptor = [[NSSortDescriptor alloc] initWithKey:@"rank" ascending:YES]; NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:rankDescriptor,nil]; [fetchRequest setSortDescriptors:sortDescriptors]; [sortDescriptors release]; [rankDescriptor release]; NSArray *fetchResults = [managedObjectContext executeFetchRequest:fetchRequest error:&error]; [fetchRequest release]; return fetchResults; Right now that is crashing with the following: Invalid keypath section passed to setPropertiesToFetch:

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  • How can I programmatically position a view using relative points?

    - by Steve Madsen
    What is the best way to position a view relative to the size of its superview, when the bounds of the superview are not yet known? I am trying to avoid hard-coding coordinates if it is at all possible. Perhaps this is silly, and if so, that's a perfectly acceptable answer. I've run into this many times when working with custom UI. The most recent example is that I'm trying to replace the UINavigationItem plain-text title with a custom view. I want that view to fill the superview, but in addition, I want a UIActivityIndicatorView on the right side, inset about 2 pixels and centered vertically. Here's the code: - (void) viewDidLoad { [super viewDidLoad]; customTitleView = [[UIView alloc] initWithFrame:CGRectZero]; customTitleView.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth; titleLabel = [[UILabel alloc] initWithFrame:CGRectZero]; titleLabel.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth; titleLabel.lineBreakMode = UILineBreakModeWordWrap; titleLabel.numberOfLines = 2; titleLabel.minimumFontSize = 11.0; titleLabel.font = [UIFont systemFontOfSize:17.0]; titleLabel.adjustsFontSizeToFitWidth = YES; [customTitleView addSubview:titleLabel]; spinnerView = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite]; spinnerView.center = CGPointMake(customTitleView.bounds.size.width - (spinnerView.bounds.size.width / 2) - 2, customTitleView.bounds.size.height / 2); spinnerView.hidesWhenStopped = YES; [customTitleView addSubview:spinnerView]; self.navigationItem.titleView = customTitleView; [customTitleView release]; } Here's my problem: at the time that this code runs, customTitleView.bounds is still zeroes. The auto-resizing mask hasn't had a chance to do its thing yet, but I very much want those values so that I can compute the relative positions of other sub-views (here, the activity indicator). Is this possible without being ugly?

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  • Removing Objects From NSMutableArray

    - by Garry
    Hi, I have a NSMutableArray that contains all the calendars on my system (as CalCalendar objects): NSMutableArray *calendars = [[CalCalendarStore defaultCalendarStore] calendars]; I want to remove from calendars any CalCalendar objects whose title does not include the string @"work". I've tried this: for (CalCalendar *cal in calendars) { // Look to see if this calendar's title contains "work". If not - remove it if ([[cal title] rangeOfString:@"work"].location == NSNotFound) { [calendars removeObject:cal]; } } The console is complaining that: *** Collection <NSCFArray: 0x11660ccb0> was mutated while being enumerated. And things go bad. Obviously it would seem you can't do what I want to do this way so can anyone suggest the best way to go about it? Thanks,

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  • Controllers in Document-based application

    - by Richard Ibarra
    Hi I've tried to setup a controller for a document in a document based application, and i'm not sure what is the correct for doing that. In MyDocument.xib I have set the File's Owner as MyDocument class and the I connected the outlets and actions to it but it doesn't seem to work Could anybody give me a hand on this? Cheers

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  • Adding custom UITableViewCell crashes the simulator.

    - by nevva
    Im trying to build my application using a custom UITableViewCell. This is the code in my UIViewController that adds the viewCell to the table: - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { NSLog(@"------- Tableview --------"); static NSString *MyIdentifier = @"MyIdentifier"; MyIdentifier = @"aCellIdentifier"; MyTableCell *cell = (MyTableCell *)[tableView dequeueReusableCellWithIdentifier:MyIdentifier]; if(cell == nil) { NSArray *[[NSBundle mainBundle] loadNibNamed:@"tblCellView" owner:self options:nil]; cell = tblCell; } [cell setLabelText:[NSString stringWithFormat:@"indexpath.row: %d", indexPath.row]]; //cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:MyIdentifier] autorelease]; return cell; } if i uncomment the line above "return cell" it returns a regular UITableViewCell without any errors, but as soon as i try to implement my custom cell it crashes with this error: ------- Tableview -------- 2010-04-23 11:17:33.163 SogetGolf[26935:40b] * Assertion failure in -[UITableView _createPreparedCellForGlobalRow:withIndexPath:], /SourceCache/UIKit_Sim/UIKit-984.38/UITableView.m:4709 2010-04-23 11:17:33.164 SogetGolf[26935:40b] * Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'UITableView dataSource must return a cell from tableView:cellForRowAtIndexPath:' 2010-04-23 11:17:33.165 SogetGolf[26935:40b] Stack: ( ... I have configured the .xib file as one should with the proper outlets. And the identifier of the UITableViewCell corresponds with name im trying to load from NSBundle

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  • HTTPS on iPhone

    - by Rob
    I need to be able to use https to connect to a server and I'm wondering if there's recommended way of doing this on the iPhone that's NOT: - an undocumented api call - does not require manually storing certificates in the app bundle Thanks all.

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  • How do you call a method for an Objective-C object's superclass from elsewhere?

    - by executor21
    If you're implementing a subclass, you can, within your implementation, explicitly call the superclass's method, even if you've overridden that method, i.e.: [self overriddenMethod]; //calls the subclass's method [super overriddenMethod]; //calls the superclass's method What if you want to call the superclass's method from somewhere outside the subclass's implementation, i.e.: [[object super] overriddenMethod]; //crashes Is this even possible? And by extension, is it possible to go up more than one level within the implementation, i.e.: [[super super] overriddenMethod]; //will this work?

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  • Differences in accessing resources between Simulator and Device?

    - by Tony
    Is there some difference between the way that bundle resources can be accessed on the iPhone simulator versus a device (in my case, an iPad)? I am able to access a file on the former, but not the latter. NSString *filePath = [NSString stringWithFormat:@"%@%@",[[NSBundle mainBundle] bundlePath], @"/AppResources/html/pages/quickHelp.html"]; BOOL fileExists = [[NSFileManager defaultManager] fileExistsAtPath:filePath]; // fileExists == YES in the debugger on both the simulator and the device NSString *path = [NSString stringWithFormat:@"AppResources/html/pages/%@", contentsFileName]; NSString *pathForURL = [[NSBundle mainBundle] pathForResource:path ofType:@"html"]; NSURL *url = [NSURL fileURLWithPath:pathForURL isDirectory:NO]; The code above works fine in the simulator, but on the device pathForResource:path returns nil, so the last line throws a 'nil string parameter' exception. Am I missing something obvious? edit: Of course, in the above @"quickHelp" is being passed in the contentsFileName var. edit2: if it makes any difference, in my build settings "Base SDK" is set to "iPhone Device 4.0", and "iPhone OS Deployment Target" is set to "iPhone OS 3.1.3". Any other settings that might have an influence?

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  • Disable colour change when source list loses focus

    - by ICR
    When an item is selected in the source list it is highlighted in blue. When another element on the window is selected, however, the highlight becomes a lighter blue as the source list is no longer focused. I would like to change the behaviour so the item is always the darker blue, the same behaviour as seen in Finder.

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  • Format textfield while typing Ios

    - by BBios
    Ive seen other examples and tried - (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string I am not sure what I am doing wrong, I just started coding my first Iphone App This is what I am trying to do I have 4 textfields and each has a limit on number of letters while typing I have done this using the below code - (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string { int valid; NSString *cs2 = [textField.text stringByReplacingCharactersInRange:range withString:string]; // int charCount = [cs2 length]; if(textField == cvv){ valid = 4; }else if(textField == cardName) { valid=26; }else if(textField == expDate) { valid=5; // if (charCount == 2 ) { // textField.text = [cs2 stringByAppendingString:@"/"]; // textField.text = cs2; // return YES; // } }else if(textField == acNumber) { valid=19; } return !([cs2 length] > valid); Works fine till here, I have a textfield where the user enters Exp date and would like to format it as if I am entering 112 then it should display as 01/12 and if I enter 2 then it should display as 1122 I tried checking if the length of the textfield value is 2 then append a / but then that gives me when I enter 12 it gives 11/22

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  • How to set the the height of cell progamatically without using nib file ?

    - by srikanth rongali
    This is my program - (void)viewDidLoad { [super viewDidLoad]; // Uncomment the following line to display an Edit button in the navigation bar for this view controller. self.title = @"Library"; self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"Close" style:UIBarButtonItemStyleBordered target:self action:@selector(close:)]; // self.tableView.rowHeight = 80; } -(void)close:(id)sender { // } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"Cell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:CellIdentifier] autorelease]; UILabel *dateLabel = [[UILabel alloc]init]; dateLabel.frame = CGRectMake(85.0f, 6.0f, 200.0f, 20.0f); dateLabel.tag = tag1; [cell setAccessoryType:UITableViewCellAccessoryDisclosureIndicator]; cell.contentView.frame = CGRectMake(0.0f, 0.0f, 320.0f, 80.0f); [cell.contentView addSubview:dateLabel]; [dateLabel release]; } // Set up the cell... //[(UILabel *)[cell viewWithTag:tag1] setText:@"Date"]; cell.textLabel.text = @"Date"; return cell; } I am setting the frame size of cell in tableView: but the cell is in default size only. I mean the height I set was 80 but it was not set as 80 height. How can I make it. Thank You

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  • How can we detect a touch of a sprite?

    - by srikanth rongali
    I have two sprites in my app. Both should have touches enabled and both touches are independent of one another. And if I touch the screen (not on sprites) it should have different touches. My problem is all three sprite1, sprite2, remaining screen should have independent touches. But my program is taking all the touches as same. How can I make them as what I needed ? Thank You.

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  • scrolling a readonly cell in NSTableview?

    - by John Velman
    I have a table that the user should not be able to edit directly (although user actions may cause changes). One column may contain a string too long for any reasonable size cell, so to see everything there, the user needs to scroll the cell (using arrow keys, for example). If I make either the column or cell not editible, I loose the ability to scroll the cell. If I make it editable, of course, I loose the ability to keep the user from changeing it. (I'm using NSArray controller and a couple of NSObject controllers to get from the model to the table view using bindings. Binding compliance via @property(copy) and @synthesize. Updating the model with setXXXX:xxx). Thanks, John Velman

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  • WebView with NSShadow slowdown

    - by Rodrigo
    I have a webview that shows some animated boxes, but it slows down and lags horribly when I put a drop shadow in the view. Without the shadow, the webview contents animate smoothly. I achieved a similar effect as safari/chrome when you do a elastic scroll with the touchpad. Looks nice! But doesnt run as smooth as in my inspirations. Here is the snippet of the shadow setting: NSShadow *dropShadow = [[NSShadow alloc] init]; [dropShadow setShadowColor:[NSColor blackColor]]; [dropShadow setShadowOffset:NSMakeSize(0, 0)]; [dropShadow setShadowBlurRadius:5.0]; [webview setWantsLayer: YES]; [webview setShadow: dropShadow]; [dropShadow release]; -- My question is: How can I work around this problem?

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