如何让处理程序重复 UIView animateWithDuration？

Question

我正在使用 UIView 类方法 animateWithDuration 来重复我的视图动画。我怎样才能拥有一个可用于稍后停止此动画的处理程序？例如，重复的动画在一种方法中启动，我需要稍后从另一种方法停止它。

Answer 1

假设您已经创建了一个取消属性，您可以执行类似的操作。如注释中所述，完成块的 startAnimation 调用需要包装在异步调用中以避免堆栈溢出。请务必将“id”替换为您实际拥有的任何类类型。

- (void)startAnimation {
    [UIView animateWithDuration:1.0
                          delay:0.0
                        options:UIViewAnimationOptionCurveLinear | UIViewAnimationOptionAllowUserInteraction
                     animations:^(void) {
                         //animate
                     }
                     completion:^(BOOL finished) {
                         if(!self.canceled) {
                             __weak id weakSelf = self;
                             [[NSOperationQueue mainQueue] addOperationWithBlock:^{
                                 [weakSelf startAnimation];
                             }];
                         }
                     }
     ];
}

Answer 2

动画的目的是重复地动画图像的弹跳。当不用担心手动停止它时，您只需要设置三个属性(UIViewAnimationOptionCurveEaseIn | UIViewAnimationOptionAutoreverse | UIViewAnimationOptionRepeat)和用于移动图像的动画块代码 - self.image.center = CGPointMake (self.image.center.x, self.image.center.y+25); 这是动画的完整代码：

[UIView animateWithDuration:0.5 delay:0 options:( UIViewAnimationOptionCurveEaseIn | 
 UIViewAnimationOptionAutoreverse | UIViewAnimationOptionRepeat | 
 UIViewAnimationOptionAllowUserInteraction) animations:^{self.image.center = 
 CGPointMake(self.image.center.x, self.image.center.y+25);} completion:nil];

就是这样。但如果您需要手动控制，则需要一些额外的代码。首先，根据 jaminguy 的说法，您需要有一个 BOOL 属性来指示循环/停止 (self.playAnimationForImage) 动画，并使用从其他地方调用的动画代码清理单独的方法。这是方法：

-(void)animateImageBounce{
 [UIView animateWithDuration:0.5 delay:0 options:( 
  UIViewAnimationOptionCurveEaseIn | UIViewAnimationOptionAutoreverse |  
  UIViewAnimationOptionAllowUserInteraction) animations:^{self.image.center = 
  CGPointMake(self.image.center.x, self.image.center.y+25);} completion:^(BOOL finished){if 
  (finished && self.playAnimationForImage){
    self.image.center = CGPointMake(self.image.center.x, self.image.center.y-25); 
    [self animateImageBounce];
  }}]; 

这是从某个方法调用动画的开始

-(void)someMethod{
...
self.playAnimationForFingers = YES;
[self animateImageBounce];

}

我要注意的是，在手动控制中，您需要在下一次递归调用之前将图像的 center.y 重置回来被执行。

Answer 3

实际上，递归调用的解决方案对我来说并不奏效。动画开始表现得很奇怪：每 2-3 个动画重复周期我就会出现动画中断。在项目的第一个弹跳部分（向下移动项目）之后，第二部分（向上移动）几乎立即执行。我认为这与递归调用有关。

因此，我拒绝使用它。解决方案是使用自动反转和重复选项启动动画，并在完整块中检查标志 (self.playAnimationForFingers) 是否指示停止动画。

-(void)animateFingersForLevelCompleteScreen{
  //fix: reset the place of bouncing fingers (starting place). 
  //Otherwise the fingers will slowly move to the bottom at every level. 
  //This resetting is not working when placed inside UIView 
  //animate complete event block

  self.image.center = CGPointMake(10 + self.image.frame.size.width/2, 
                                  95 + self.image.frame.size.height/2); 

  [UIView animateWithDuration:0.5 delay:0 
    options:(UIViewAnimationOptionCurveEaseIn | 
             UIViewAnimationOptionAutoreverse | 
             UIViewAnimationOptionRepeat |
             UIViewAnimationOptionAllowUserInteraction) 
    animations:^{
      self.image.center = CGPointMake(self.image.center.x, 
                                      self.image.center.y+25);
    } 
    completion:^(BOOL finished){
      /*finished not approapriate: finished will not be TRUE if animation 
      was interrupted. It is very likely to happen because animation repeats && */
      if (!self.playAnimationForFingers){
         [UIView setAnimationRepeatAutoreverses:NO]; 
      }
  }];
}

Answer 4

你可以使用 CABasicAnimation 来代替。

    CABasicAnimation *appDeleteShakeAnimation = [CABasicAnimation animationWithKeyPath:@"transform.rotation"];
appDeleteShakeAnimation.autoreverses = YES;
appDeleteShakeAnimation.repeatDuration = HUGE_VALF;
appDeleteShakeAnimation.duration = 0.2;
appDeleteShakeAnimation.fromValue = [NSNumber numberWithFloat:-degreeToRadian(5)];
appDeleteShakeAnimation.toValue=[NSNumber numberWithFloat:degreeToRadian(5)];
[self.layer addAnimation:appDeleteShakeAnimation forKey:@"appDeleteShakeAnimation"];

然后当你想停止它时你可以打电话

[self.layer removeAnimationForKey:@"appDeleteShakeAnimation"];