Open Radar

 
09-Oct-2009 10:57 AM Coleman Nitroy:
Summary:
Animating a UIButton produces different results then animating a different type of UIView.  

Steps to Reproduce:
        // Using a UIImageView to demonostrate the working animations.
        CGRect frame = CGRectMake(0,0, 50, 50);      
	UIImageView *zoomView = [[UIImageView alloc] initWithFrame:frame];
        zoomView.image = [UIImage imageNamed:@"someimage.png"];
	[self.view addSubview:zoomView];

	[UIView beginAnimations:nil context:NULL];
	[UIView setAnimationDuration: 2];
	frame.origin.x = 20;
        frame.size.width = 100;
	frame.size.height = 100;
	zoomView.frame = frame;
	[UIView commitAnimations];

        // Using a custom UIButton with the same frame translations
        frame = CGRectMake(0,0, 50, 50);      
	UIButton *zoomView = [[UIButton alloc] initWithFrame:frame];
        [zoomView setImage:[UIImage imageNamed:@"someimage.png"] forState:UIControlStateNormal];
	[self.view addSubview:zoomView];

	[UIView beginAnimations:nil context:NULL];
	[UIView setAnimationDuration: 2];
	frame.origin.x = 20;
	frame.size.width = 100;
	frame.size.height = 100;
	zoomView.frame = frame;
	[UIView commitAnimations];

Expected Results:
Both views should animate along the X axis 20, and grow to 100x100 in size.

Actual Results:
The UIImageView moves along the X axis and grows to 100x100. The UIButton moves along the X axis but frame size changes instantly instead of over 2 seconds time set by [UIView setAnimationDuration:2];

Regression:
I am able to produce this incorrect behavior on all SDK version 3.0, on the iPhone simulator, and on a iPhone 3G and iPhone 3GS. When the button type is of rounded rect the animation works as expected. This issue only pertains to buttons of the custom type.

Notes:
Current workaround is to subclass UIViews and handle touch events manually instead of using a UIButton. This leads to a lot more work to mimic fully the behavior of a UIButton.