我使用UILabel
为屏幕上的CATransition
设置为“蒸发”动画。
我希望标签文字变为绿色,然后离开屏幕。
以下代码可以很好地“蒸发”标签,但在制作动画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
无法使用CABasicAnimation
,因为标签文字正在发生变化。
我做错了什么以及如何解决?
答案 0 :(得分:2)
你基本上想要嵌套动画,或者在某种意义上,你想要一个完整块类型的东西
我能想到的最接近的是使用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:@" "];
}