UIView动画出现问题-一次执行同一动画不起作用

Question

I need to flip a card and then flip it back. I have written code to do that with no trouble. The trouble comes because users can flip this card back and forth as many times as they want, and it seems that the effect is cumulative. On the second try, the card spins like a top. I'm not completely surprised, as there only seems to be a way to add animation, not clear one from the view. Is there a way to 're-set' a UIView of any animations I had previously committed? Is there a way to capture it and re-use it without committing a new one? Or am I missing something obvious? This is my code:

if (self.flipped) {
    [UIView beginAnimations:nil context:nil];
    [UIView setAnimationDuration:1.0];
    [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromLeft
                           forView:self
                             cache:YES];
    [imageView removeFromSuperview];
    [UIView commitAnimations];
    self.flipped = NO;
} else {
    [UIView beginAnimations:nil context:nil];
    [UIView setAnimationDuration:1.0];
    [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromRight
                           forView:self
                             cache:YES];
    [self addSubview:imageView];
    [UIView commitAnimations];
    self.flipped = YES;
}

Thanks for reading.

Answer 1

To cancel all ongoing animations:

#import <QuartzCore/QuartzCore.h>

...

[view.layer removeAllAnimations];

To start a new animation that kills existing animations, if any, and starts the movement from wherever the view currently is — which I think is what you want:

[UIView beginAnimations:nil context:nil];
[UIView setAnimationBeginsFromCurrentState:YES];

... and the rest of it ...

[UIView commitAnimations];

Hopefully one of those will solve your problem.

Answer 2

Whatever your "self" is, put it in a containing view called foo, and then change your setAnimation... line to this:

    [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromRight
                       forView:foo
                         cache:YES];