UIImageView动画完成后的访问方法

Question

我将一组图像加载到 UIImageView 中，我正在通过一个周期对其进行动画处理。显示图像后，我希望调用 @selector 以关闭当前视图控制器。使用此代码可以很好地动画图像：

NSArray * imageArray = [[NSArray alloc] initWithObjects:
                        [UIImage imageNamed:@"HowTo1.png"], 
                        [UIImage imageNamed:@"HowTo2.png"],
                        nil];
UIImageView * instructions = [[UIImageView alloc] initWithFrame:[[UIScreen mainScreen] bounds]];

instructions.animationImages = imageArray;
[imageArray release];
instructions.animationDuration = 16.0;
instructions.animationRepeatCount = 1;
instructions.contentMode = UIViewContentModeBottomLeft;
[instructions startAnimating];
[self.view addSubview:instructions];
[instructions release];

16 秒后，我想调用一个方法。我查看了UIView 类方法setAnimationDidStopSelector:，但我无法让它与我当前的动画实现一起工作。有什么建议吗？

谢谢。

Answer 1

您可以创建一个计时器以在动画持续时间后触发。回调可以处理您想要在动画完成后执行的逻辑。在您的回调中，请务必检查动画的状态[UIImageView isAnimating]，以防您需要更多时间让动画完成。

Answer 2

使用performSelector:withObject:afterDelay::

[self performSelector:@selector(animationDidFinish:) withObject:nil
    afterDelay:instructions.animationDuration];

或使用dispatch_after:

dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, instructions.animationDuration * NSEC_PER_SEC);
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
    [self animationDidFinish];
});

Answer 3

在 ImageView.m 中

- (void) startAnimatingWithCompleted:(void (^)(void))completedHandler {
if (!self.isAnimating) {
    [self startAnimating];
    dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, self.animationDuration * NSEC_PER_SEC);
    dispatch_after(popTime, dispatch_get_main_queue(),completedHandler);       
}}

Answer 4

没有办法用 UIImageView 精确地做到这一点。在大多数情况下使用延迟会起作用，但是在动画发生在屏幕上之前调用 startAnimating 之后可能会有一些延迟，因此它不精确。而不是使用 UIImageView 这个动画尝试使用 CAKeyframeAnimation ，它会在动画完成时调用委托方法。大致如下：

NSArray * imageArray = [[NSArray alloc] initWithObjects:
                    (id)[UIImage imageNamed:@"HowTo1.png"].CGImage, 
                    (id)[UIImage imageNamed:@"HowTo2.png"].CGImage,
                    nil];
UIImageView * instructions = [[UIImageView alloc] initWithFrame:[[UIScreen mainScreen] bounds]];

//create animation
CAKeyframeAnimation *anim = [CAKeyframeAnimation animation];
[anim setKeyPath:@"contents"];
[anim setValues:imageArray];

[anim setRepeatCount:1];
[anim setDuration:1];
anim.delegate = self; // delegate animationDidStop method will be called

CALayer *myLayer = instructions.layer;

[myLayer addAnimation:anim forKey:nil];

然后只需实现animationDidStop委托方法

Answer 5

使用这种方法，您可以避免在 imageView 由于图像加载缓慢而仍在动画时触发计时器。 您可以通过这种方式同时使用performSelector: withObject: afterDelay: 和 GCD：

[self performSelector:@selector(didFinishAnimatingImageView:)
           withObject:imageView
           afterDelay:imageView.animationDuration];

/!\self.imageView.animationDuration必须在startAnimating之前配置，否则为0

如果-(void)didFinishAnimatingImageView:创建一个后台队列，检查isAnimating属性，而不是在主队列上执行其余部分

- (void)didFinishAnimatingImageView:(UIImageView*)imageView
{

   dispatch_queue_t backgroundQueue = dispatch_queue_create("com.yourcompany.yourapp.checkDidFinishAnimatingImageView", 0);
   dispatch_async(backgroundQueue, ^{

       while (self.imageView.isAnimating)
           NSLog(@"Is animating... Waiting...");

       dispatch_async(dispatch_get_main_queue(), ^{

          /* All the rest... */

       });

   });

}

Answer 6

你可以简单的使用这个分类UIImageView-AnimationCompletionBlock

对于 Swift 版本：UIImageView-AnimationImagesCompletionBlock

查看本课程的自述文件..

在项目中添加 UIImageView+AnimationCompletion.h 和 UIImageView+AnimationCompletion.m 文件，然后将 UIImageView+AnimationCompletion.h 文件导入到您所在的位置想用这个..

例如。

NSMutableArray *imagesArray = [[NSMutableArray alloc] init];
for(int i = 10001 ; i<= 10010 ; i++)
    [imagesArray addObject:[UIImage imageNamed:[NSString stringWithFormat:@"%d.png",i]]];

self.animatedImageView.animationImages = imagesArray;
self.animatedImageView.animationDuration = 2.0f;
self.animatedImageView.animationRepeatCount = 3;
[self.animatedImageView startAnimatingWithCompletionBlock:^(BOOL success){
 NSLog(@"Animation Completed",);}];

Answer 7

从 GurPreet_Singh 答案创建 Swift 版本 (UIImageView+AnimationCompletion) 我无法为 UIImageView 创建扩展，但我相信这很容易使用。

class AnimatedImageView: UIImageView, CAAnimationDelegate {

    var completion: ((_ completed: Bool) -> Void)?

    func startAnimate(completion: ((_ completed: Bool) -> Void)?) {
        self.completion = completion
        if let animationImages = animationImages {
            let cgImages = animationImages.map({ $0.cgImage as AnyObject })
            let animation = CAKeyframeAnimation(keyPath: "contents")
            animation.values = cgImages
            animation.repeatCount = Float(self.animationRepeatCount)
            animation.duration = self.animationDuration
            animation.delegate = self

            self.layer.add(animation, forKey: nil)
        } else {
            self.completion?(false)
        }
    }

    func animationDidStop(_ anim: CAAnimation, finished flag: Bool) {
        completion?(flag)
    }
}


let imageView = AnimatedImageView(frame: CGRect(x: 50, y: 50, width: 200, height: 135))
imageView.image = images.first
imageView.animationImages = images
imageView.animationDuration = 2
imageView.animationRepeatCount = 1
view.addSubview(imageView)

imageView.startAnimate { (completed) in
     print("animation is done \(completed)")
     imageView.image = images.last
}