UIView removeFromSuperView animation delay

Question

I have a method which animates one of the subviews of UIWindow and then removes it from UIWindow using removeFromSuperview. But when I put removeFromSuperview after animation block, the animation never shows, because removeFromSuperview removes the UIView from UIWindow before the animation plays :-( How can I delay removeFromSuperview so the animation plays first, and then subview is removed? I tried [NSThread sleepForTimeInterval:1]; after animation block but that didn't have desired effect, because animation sleeps too for some reason.

My code for this method:

  - (void) animateAndRemove
    {
     NSObject *mainWindow = [[UIApplication sharedApplication] keyWindow];

     [UIView beginAnimations:nil context:nil];
        [UIView setAnimationDuration:0.8]; 
     UIView *theView = nil;
     for (UIView *currentView in [mainWindow subviews])
     {
      if (currentView.tag == 666)
      {
       currentView.backgroundColor = [UIColor colorWithRed:0.8 green:0.8 blue:0.8 alpha:0.0];
       theView = currentView;
       }
     }
     [UIView setAnimationTransition:  UIViewAnimationTransitionNone forView:theView cache:YES];
      [UIView commitAnimations]; 



 //[NSThread sleepForTimeInterval:1];

 [theView removeFromSuperview];


    }

Answer 1

You should use the delegation mechanism in animation blocks to decide what to do when the animation ends. For your case, use

[UIView beginAnimations:nil context:nil];
[UIView setAnimationDelegate:theView];
[UIView setAnimationDidStopSelector:@selector(removeFromSuperview)];
 ....

This ensures [theView removeFromSuperview] will be called after the animation is completed.

Answer 2

If you're targetting iOS 4.0 upwards you can use animation blocks:

[UIView animateWithDuration:0.2
     animations:^{view.alpha = 0.0;}
     completion:^(BOOL finished){ [view removeFromSuperview]; }];

(above code comes from Apple's UIView documentation)