beginAnimations: subview's animation slower then view's animation - iphone

Question

I have a little problem, I try to display a view with an animation in this way:
self.vistaAiuti = [[UIView alloc] initWithFrame:CGRectMake(10, -200, 300, 200)];
self.vistaAiuti.backgroundColor = [UIColor blueColor];
UIButton *closeButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
closeButton.frame = CGRectMake(50, 140, 220, 40);
[closeButton setTitle:#"Go back" forState:UIControlStateNormal];
[closeButton addTarget:self action:#selector(closeView:) forControlEvents:UIControlEventTouchUpInside];
[self.vistaAiuti addSubview:closeButton];
[self.view addSubview:self.vistaAiuti];
[UIView beginAnimations:#"MoveView" context:nil];
[UIView setAnimationCurve:UIViewAnimationCurveEaseIn];
[UIView setAnimationDuration:0.5f];
self.vistaAiuti.frame = CGRectMake(10, 0, 300, 200);
[UIView commitAnimations];
and this for close it:
[UIView beginAnimations:#"MoveView" context:nil];
[UIView setAnimationCurve:UIViewAnimationCurveEaseIn];
[UIView setAnimationDuration:0.5f];
self.vistaAiuti.frame = CGRectMake(10, -200, 300, 0);
[UIView commitAnimations];
the problem is that the button on vista aiuto is slower then the vistaAiuti, so when I close the view the button remains behind for some second...what I have to do for for have the same velocitiy?

Answer 1

The problem is that the vistaAiuti frame is being set to zero height in the close animation. The button appears to lag, but what's really happening is that the parent view underneath is shrinking to zero height and -200 origin.y.
Change the close animation target frame to:
self.vistaAiuti.frame = CGRectMake(10, -200, 300, 200);
Also, some other advice:
Separate the creation of the view from showing it. This way you don't add another subview every time you want to show it.
- (void)addVistaAiutiView {
// your creation code
self.vistaAiuti = [[UIView alloc] initWithFrame:CGRectMake(10, -200, 300, 200)];
self.vistaAiuti.backgroundColor = [UIColor blueColor];
UIButton *closeButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
closeButton.frame = CGRectMake(50, 140, 220, 40);
[closeButton setTitle:#"Go back" forState:UIControlStateNormal];
[closeButton addTarget:self action:#selector(closeView:) forControlEvents:UIControlEventTouchUpInside];
[self.vistaAiuti addSubview:closeButton];
[self.view addSubview:self.vistaAiuti];
}
Use block animation, it's much more compact to write and easy to read
- (BOOL)vistaAiutiIsHidden {
return self.vistaAiuti.frame.origin.y < 0.0;
}
- (void)setVistaAiutiHidden:(BOOL)hidden animated:(BOOL)animated {
if (hidden == [self vistaAiutiIsHidden]) return; // do nothing if it's already in the state we want it
CGFloat yOffset = (hidden)? -200 : 200; // move down to show, up to hide
NSTimeInterval duration = (animated)? 0.5 : 0.0; // quick duration or instantaneous
[UIView animateWithDuration:duration animations: ^{
self.vistaAiuti.frame = CGRectOffset(0.0, yOffset);
}];
}