swap background image?

[kend0g187]

I'm trying to swap the background image when the user swipes the screen. I have this code:

- (void)viewDidLoad {
UIImageView *background = [[UIImageView alloc] initWithImage: [UIImage imageNamed: @"img1.png"]];
[background setFrame: CGRectMake( 0.0, 44.0, 320.0, 366.0 )];
[self.view insertSubview: background atIndex: 0];
[background release];
}

My swipe gesture recognizer calls this function:

- (void) swapBackgroundRight {
UIImageView *newBackground = [[UIImageView alloc] initWithImage: [UIImage imageNamed: @"img2.png"]];
[newBackground setFrame: CGRectMake( -320.0, 44.0, 320.0, 366.0 )];
[self.view insertSubview: newBackground atIndex: 1];
[newBackground release];
[UIView beginAnimations: @"Slide In" context: nil];
[UIView setAnimationDuration: 0.3];
[UIView setAnimationCurve: UIViewAnimationCurveEaseOut];
[[self.view.subviews objectAtIndex: 0] setFrame: CGRectMake( 320.0, 44.0, 320.0, 366.0 )];
	[newBackground setFrame: CGRectMake( 0.0, 44.0, 320.0, 366.0 )];
	[UIView commitAnimations];
	[[self.view.subviews objectAtIndex: 0] performSelector: @selector(removeFromSuperview) withObject: nil afterDelay: 0.3];
}

When I step through the code, every line executes as expected, but after the method finishes, I get EXC_BAD_ACCESS. This is driving me crazy. Any ideas?

[Objective Zero]

Try this for your second code set:

- (void) swapBackgroundRight {
UIImageView *newBackground = [[UIImageView alloc] initWithImage: [UIImage imageNamed: @"img2.png"]];
[newBackground setFrame: CGRectMake( -320.0, 44.0, 320.0, 366.0 )];
[self.view insertSubview: newBackground atIndex: 1];
[UIView beginAnimations: @"Slide In" context: nil];
[UIView setAnimationDuration: 0.3];
[UIView setAnimationCurve: UIViewAnimationCurveEaseOut];
[[self.view.subviews objectAtIndex: 0] setFrame: CGRectMake( 320.0, 44.0, 320.0, 366.0 )];
	[newBackground setFrame: CGRectMake( 0.0, 44.0, 320.0, 366.0 )];
	[UIView commitAnimations];
	[[self.view.subviews objectAtIndex: 0] performSelector: @selector(removeFromSuperview) withObject: nil afterDelay: 0.3];
[newBackground release];
}

[kend0g187]

Didn't work. Based on my understanding of memory management, when I add 'newBackground' to the view it increases it's retain count to 2, so if I release it right away it still has a retain count of 1 and should still stick around.

The weird thing is every once-in-a-while this code will work. The full code actually swaps between between 7 images like so:

if( backgroundIndex > 1 )
		backgroundIndex--;
	else 
		backgroundIndex = kNumBackgrounds;
	NSString *newName = [NSString stringWithFormat: @"texture%d.png", backgroundIndex];
	UIImageView *newBackground = [[UIImageView alloc] initWithImage: [UIImage imageNamed: newName]];
	[newName release];

In the rare case that the code runs once, it will fail on the 7th run the I try to set the first image back as the backgound. Don't know if that helps anyone. It just makes me more confused.

Wow, as I was typing that I realized I'm releasing a string that I never allocated. Been playing with my code for about 4 hours and never noticed it.

[Objective Zero]

What if you just take out [newBackground release];

Will that do it? Also did you try autorelease?

What does the console say when it crashes?