[英]UILabel's layer doesn't update color while animating
我正在对UILabel
进行动画处理,以使用CATransition
将其“蒸发”出屏幕。
我希望标签文本变为绿色,然后移出屏幕。
以下代码可以很好地“蒸发”标签,但在进行动画处理之前不会更改其颜色:
CATransition *transition = [CATransition animation];
transition.beginTime = CACurrentMediaTime();
transition.duration = 0.4;
transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionDefault];
transition.type = kCATransitionPush;
transition.subtype = kCATransitionFromTop;
[self.displayLabel.layer addAnimation:transition forKey:@"evaporate"];
self.displayLabel.textColor = [self greenColor];
self.displayLabel.text = @" ";
在标签上调用setNeedsDisplay
不起作用。
标签文本正在更改,因此无法使用CABasicAnimation
。
我在做什么错,我该如何解决?
基本上,您需要嵌套动画,或者从某种意义上讲,是在寻找完成块类型的东西。
我能想到的最接近的方法是使用CATransition
委托
-(IBAction)btnTest:(UIButton *)sender
{
//[1] Animate text color change
CATransition *animation = [CATransition animation];
[animation setDelegate:self]; //important
[animation setRemovedOnCompletion:YES]; //better to remove the animation
[animation setBeginTime:CACurrentMediaTime()]; //not really needed
[animation setDuration:0.4];
[animation setTimingFunction:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionDefault]];
[animation setType:kCATransitionFade];
//you can specify any key name or keep it nil. doesn't make a difference
[self.displayLabel.layer addAnimation:animation forKey:@"changeTextColor"];
[self.displayLabel setTextColor:[UIColor greenColor]];
}
#pragma mark - CATransition Delegate
-(void)animationDidStop:(CAAnimation *)anim finished:(BOOL)flag
{
//[2] Animate text sublayer
/*
The following CATransition should not set a delegate
otherwise this animation will loop continously
*/
CATransition *animation = [CATransition animation];
[animation setRemovedOnCompletion:YES]; //better to remove the animation
[animation setBeginTime:CACurrentMediaTime()]; //not really needed
[animation setDuration:0.4];
[animation setTimingFunction:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionDefault]];
[animation setType:kCATransitionPush];
[animation setSubtype:kCATransitionFromTop];
//you can specify any key name or keep it nil. doesn't make a difference
[self.displayLabel.layer addAnimation:animation forKey:@"changeText"];
[self.displayLabel setText:@" "];
}
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