Extending a view to the left side, animated - objective-c

Question

I have a view that I want to extend on the left side using an animation. All borders but the left one should remain the same, so the x position and the width of the view are changing.
I use this code:
[UIView beginAnimations:nil context:nil];
[UIView setAnimationDuration:5.0];
self.frame = CGRectMake(self.frame.origin.x-100,
self.frame.origin.y,
self.frame.size.width+100,
self.frame.size.height);
[UIView commitAnimations];
If I run this code, the width of the view is set to the new value immediately and then the view is moved to the new x point, but why? How can I change this behaviour?
Thanks for your ideas!

Answer 1

Your code runs fine for me. How are you running it? Calling -setFrame is the right choice for what you're doing. Here is what my custom view looks like:
#import "TestView.h"
#implementation TestView
- (id)initWithFrame:(CGRect)frame {
if ((self = [super initWithFrame:frame])) {
// Initialization code
}
return self;
}
- (void)dealloc {
[super dealloc];
}
- (void)go;
{
[UIView beginAnimations:nil context:nil];
[UIView setAnimationDuration:5.0];
self.frame = CGRectMake(self.frame.origin.x-100,
self.frame.origin.y,
self.frame.size.width+100,
self.frame.size.height);
[UIView commitAnimations];
}
#end
I create an outlet from my view controller of type TestView and connect it and set its type in IB. Then I create a button whose handler calls [customView go]; Seems to work fine.

Answer 2

Okay, I made it woring now. The problem was that my view was a UIButton and I set the title and background with the setBackground:forState: and setTitle:forState:.
It seems that the background of the view is not animatable. I use the work around that I add my own background with a UIImageView.
Thanks for your replies!