iOS - CATransition 问题 : showing end image at start

Question

在我的 UIViewController 中，我使用 image1 创建了 CALayer。

CALayer *imageLayer = [CALayer layer];
[imageLayer setBounds:CGRectMake(0.0, 0.0, 241.0, 430.0)];
[imageLayer setPosition:CGPointMake(160.0, 60.0)];
[imageLayer setAnchorPoint:CGPointMake(0.5, 0.0)];
[imageLayer setContents:(id)[UIImage imageNamed:@"image1.png".CGImage];
[imageLayer setContentsGravity:kCAGravityResizeAspect];
[self.view.layer addSublayer:imageLayer];

稍后在 UIViewController 中，我想通过使用 CATransition 推送它来更改图像。

CATransition *t = [CATransition animation];
t.beginTime = [self.view.layer convertTime:CACurrentMediaTime() + 6.5 fromLayer:nil];
t.type = kCATransitionPush;
t.subtype = kCATransitionFromRight;
[imageLayer setContents:(id)[UIImage imageNamed:@"image2.png"].CGImage];    
[imageLayer addAnimation:t forKey:nil];

当运行代码时，我从一开始就得到了 image2，过渡通过在 6.5 秒后推送自身来工作。 图1在哪里？怎么了？

正确答案: 感谢 Jacky Boy 和 Tiago Almeida。 我更正了删除行的代码

t.beginTime = [self.view.layer convertTime:CACurrentMediaTime() + 6.5 fromLayer:nil];

并添加“dispatch_after”。

现在可以了:

CATransition *t = [CATransition animation];
t.type = kCATransitionPush;
t.subtype = kCATransitionFromRight;
[imageLayer setContents:(id)[UIImage imageNamed:@"image2.png"].CGImage];    
[imageLayer addAnimation:t forKey:nil];
[CATransaction begin];
NSTimeInterval delayInSeconds = 6.5;
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
    [imageLayer setContents:(id)[UIImage imageNamed:@"image2.png"].CGImage];
    [imageLayer addAnimation:t forKey:nil];
});
[CATransaction commit];

再次感谢大家!

Answer 1

删除以下行:

t.beginTime = [self.view.layer convertTime:CACurrentMediaTime() + 1.5 fromLayer:nil];

这就是延迟动画，所以层正在设置新的内容，并且只有在层被动画化之后。如果要指定动画的持续时间:

[CATransaction begin];
[CATransaction setAnimationDuration:1.0];

CATransition *t = [CATransition animation];
t.type = kCATransitionPush;
t.subtype = kCATransitionFromRight;
[_layer setContents:(id)[UIImage imageNamed:@"image2.jpg"].CGImage];
[_layer addAnimation:t forKey:nil];


[CATransaction commit];

或更小的版本:

CATransition *t = [CATransition animation];
t.type = kCATransitionPush;
[t setDuration:2.5];
t.subtype = kCATransitionFromRight;
[_layer setContents:(id)[UIImage imageNamed:@"image2.jpg"].CGImage];
[_layer addAnimation:t forKey:nil];

---

我更喜欢这个:

CATransition *transition = [CATransition animation];
transition.type = kCATransitionPush;
transition.duration = .25f;
transition.subtype = kCATransitionFromRight;

_layer.actions = @{@"contents": transition};

当你想改变内容时:

[_layer setContents:(id)[UIImage imageNamed:@"image2.jpg"].CGImage];