ios - UIImageView 的动画在真实的 iOS 设备上效果不佳

Question

我想在应用程序启动时添加一些动画。在 iPad 模拟器上一切正常。但是当它在真正的 iPad 上运行时，框架会静止一会儿，然后开始动画。在所有帧显示之前，动画完成。这是我的代码

    - (void)viewDidAppear:(BOOL)animated
{
    NSArray *myImages = [NSArray arrayWithObjects: [UIImage imageNamed:@"1.png"], 
                         [UIImage imageNamed:@"2.png"], 
                         [UIImage imageNamed:@"3.png"], 
                         [UIImage imageNamed:@"4.png"], 
                         [UIImage imageNamed:@"5.png"],
                         [UIImage imageNamed:@"6.png"],
                         [UIImage imageNamed:@"7.png"],
                         [UIImage imageNamed:@"8.png"],
                         [UIImage imageNamed:@"9.png"],
                         [UIImage imageNamed:@"10.png"],
                         [UIImage imageNamed:@"11.png"],
                         [UIImage imageNamed:@"12.png"],
                         [UIImage imageNamed:@"13.png"],
                         [UIImage imageNamed:@"14.png"],
                         [UIImage imageNamed:@"15.png"],
                         [UIImage imageNamed:@"16.png"],
                         [UIImage imageNamed:@"17.png"],
                         [UIImage imageNamed:@"18.png"],
                         [UIImage imageNamed:@"19.png"],
                         [UIImage imageNamed:@"20.png"],
                         [UIImage imageNamed:@"21.png"],
                         [UIImage imageNamed:@"22.png"],
                         [UIImage imageNamed:@"23.png"],
                         [UIImage imageNamed:@"24.png"],
                         [UIImage imageNamed:@"25.png"],
                         [UIImage imageNamed:@"26.png"],
                         [UIImage imageNamed:@"27.png"],
                         [UIImage imageNamed:@"28.png"],
                         [UIImage imageNamed:@"29.png"],
                         [UIImage imageNamed:@"30.png"],
                         [UIImage imageNamed:@"31.png"],
                         [UIImage imageNamed:@"32.png"],
                         [UIImage imageNamed:@"33.png"],
                         [UIImage imageNamed:@"34.png"],
                         [UIImage imageNamed:@"35.png"],
                         [UIImage imageNamed:@"36.png"],
                         [UIImage imageNamed:@"37.png"],
                         [UIImage imageNamed:@"38.png"],
                         nil];   

    //myAnimatedView is UIImageView outlet
    myAnimatedView.animationImages = myImages; 
    myAnimatedView.animationDuration = 3; 
    myAnimatedView.animationRepeatCount = 1; 
    [myAnimatedView startAnimating];

    //trigger animationDone method when animation is finished
    dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, myAnimatedView.animationDuration * NSEC_PER_SEC);
    dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
        [self animationDone];
    });

Answer 1

我认为问题在于您尝试检测动画是否已完成的方式。您的方法不正确，因为它只是基于对动画的估计。

手机的 cpu 功率比使用 Mac CPU 的模拟器少得多，因此它在执行周围的事情时会变慢。因此，当您假设动画已完成加载时，您的动画尚未完成。

此外，我不明白将 Grand Central Dispatch 用作简单计时器的背后逻辑，这基本上就是您正在做的事情。

我会将逻辑更改为一个简单的计时器，我将只检查 UIImageView 的 isAnimating 值。

所以，摆脱这个:

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

并替换为:

[self performSelector:@selector(checkAnimation) withObject:nil afterDelay:0.1];

这是我们的 checkAnimation 函数:

- (void)checkAnimation {
    if (animationView.isAnimating) {
        [self performSelector:@selector(checkAnimation) withObject:nil afterDelay:0.1];
    }
    else {
        [self animationDone];
    }
}