如何循环UIAnimation？

Question

我的动画播放得很好。但在动画结束时，动画就停止了。我要动画循环。我该怎么做？这是我的代码：

    - (void) startTicker
{
    if (self.timerIsRunning) return;

    self.timerIsRunning = YES;

    NSTimer *newTimer = [NSTimer timerWithTimeInterval:(0.1) target:self selector:@selector(onTimer:) userInfo:nil repeats:YES];
    [[NSRunLoop mainRunLoop] addTimer:newTimer forMode:NSDefaultRunLoopMode];

   [UIView beginAnimations:nil context:nil];
   [UIView setAnimationDuration:100.0];
   [UIView setAnimationDelegate:self];
   [UIView setAnimationDelay:0.0];
   [UIView setAnimationDidStopSelector:@selector(moveToLeft:finished:context:)];
   [UIView commitAnimations];


}


     -(void)moveToLeft:(NSString *)animationID finished:(NSNumber *)finished context:(void *)context 
    { 

        imageView.left = 800; 
        [UIView beginAnimations:nil context:nil];
        [UIView setAnimationDuration:100.0];
        [UIView setAnimationDelay:0.0];
        [UIView setAnimationDelegate:self];
        [UIView setAnimationTransition:UIViewAnimationTransitionNone forView:self cache:YES];
        imageView.right = 800;

        [UIView setAnimationDidStopSelector:@selector(moveToLeft2:finished2:context2:)];
        [UIView commitAnimations];



    }

Answer 1

对于循环动画，最好的方法是使用块动画，这是UIView的一部分。

调用该方法时：

+ (void)animateWithDuration:(NSTimeInterval)duration delay:(NSTimeInterval)delay options:(UIViewAnimationOptions)options animations:(void (^)(void))animations completion:(void (^)(BOOL finished))completion

您可能需要的“选项”是UIViewAnimationOptionAutoreverse，并与UIViewAnimationOptionRepeat相结合。

例如：(循环闪烁红色边框)

[UIView animateWithDuration:2.0f delay:0 options:UIViewAnimationOptionAutoreverse | UIViewAnimationOptionRepeat animations:^{
    [redBorder setAlpha:0]; //first part of animation
    [redBorder setAlpha:0.5]; //second part of animation
} completion:nil];