objective-c - 核心动画动画滞后

Question

我正在尝试使用核心动画淡入一些 View 。一切都很好，直到第四个或第五个 View 淡入为止。动画停止，几秒钟后，其余 View 仅显示在屏幕上(没有动画发生)。我在第三代iPad上进行了测试，所以这不可能是硬件过时的问题。代码:

viewDidLoad

- (void)viewDidLoad {
    [super viewDidLoad];
    self.subViews = self.view.subviews;

    for (UIView *view in self.subViews) {
        view.backgroundColor = [UIColor clearColor];
        PhotoFrame *photoFrame = [[PhotoFrame alloc] init];
        photoFrame.photo.image = [UIImage imageNamed:[NSString stringWithFormat:@"test%d.jpg", arc4random() % 6 + 1]];
        [view addSubview:photoFrame];
        view.layer.opacity = 0;
    }
}

viewDidAppear

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];
    [self startAnimations];
}

开始动画

- (void)startAnimations {
    int count = 1;
    for (UIView *view in self.subViews) {
        CALayer *animationLayer = view.layer;

        CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"opacity"];
        animation.fromValue = @0.0;
        animation.toValue = @1.0;
        animation.duration = 0.3;
        animation.beginTime = CACurrentMediaTime() + count * 0.3;
        animation.removedOnCompletion = NO;
        animation.fillMode = kCAFillModeForwards;

        [animationLayer addAnimation:animation forKey:@"opacityAnimation"];
        count++;
    }
}

希望大家能够帮助我。

Answer 1

我建议切换到 UIView 动画方法，例如 animateWithDuration:animations: ，或者在提交动画时将属性设置为其最终值，而不是使用 removedOnCompletion = TRUE . 正如我在上面的评论中所说，removedOnCompletion 实际上使动画保持事件状态，并应用于渲染的每个帧。我发现当有很多动画处于事件状态时，速度会变慢。