试图将CABasicAnimation位置和图层的不透明度延迟3秒但是

Question

我试图使用setBeginTime将图层的不透明度和位置的动画延迟3秒.我已经调用了图层boxLayer.然而,动画在前3秒(该图层不应显示)中运行良好,图层将显示在其最终位置和不透明度.它不应该.组动画无法解决问题.有人可以帮忙吗？见下面的代码:

// Create an animation that will change the opacity of a layer
CABasicAnimation *fader = [CABasicAnimation animationWithKeyPath:@"opacity"];


// It will last 1 second and will be delayed by 3 seconds
[fader setDuration:1.0];
[fader setBeginTime:CACurrentMediaTime()+3.0];


// The layer's opacity will start at 0.0 (completely transparent)
[fader setFromValue:[NSNumber numberWithFloat:startOpacity]];

// And the layer will end at 1.0 (completely opaque)
[fader setToValue:[NSNumber numberWithFloat:endOpacity]];

// Add it to the layer
[boxLayer addAnimation:fader forKey:@"BigFade"];

// Maintain opacity to 1.0 JUST TO MAKE SURE IT DOES NOT GO BACK TO ORIGINAL OPACITY
[boxLayer setOpacity:endOpacity];


// Create an animation that will change the position of a layer
CABasicAnimation *mover = [CABasicAnimation animationWithKeyPath:@"position"];

// It will last 1 second and will be delayed by 3 seconds
[mover setDuration:1.0];
[mover setBeginTime:CACurrentMediaTime()+3.0];

// Setting starting position
[mover setFromValue:[NSValue valueWithCGPoint:CGPointMake(startX, startY)]];

// Setting ending position
[mover setToValue:[NSValue valueWithCGPoint:CGPointMake(endX, endY)]];

// Add it to the layer
[boxLayer addAnimation:mover forKey:@"BigMove"];

// Maintain the end position at 400.0 450.0 OTHERWISE IT IS GOING BACK TO ORIGINAL POSITION
[boxLayer setPosition:CGPointMake(endX, endY)];

Answer 1

问题是,你设置boxLayer的性质position和opacity他们的最终值.你需要:

1. 将boxLayer属性设置为它们的起始值,而不是它们的结束值(这就是为什么它从结束位置/不透明度开始...通常如果动画立即开始,这不是问题,但是因为你推迟了开始,使用结束位置是有问题的);

2. 为了您的两个动画,你必须改变removedOnCompletion,以NO和fillMode到kCAFillModeForwards(这是为了防止其恢复到完成时的原始位置的正确方法).

从而:

// Create an animation that will change the opacity of a layer
CABasicAnimation *fader = [CABasicAnimation animationWithKeyPath:@"opacity"];

// It will last 1 second and will be delayed by 3 seconds
[fader setDuration:1.0];
[fader setBeginTime:CACurrentMediaTime()+3.0];

// The layer's opacity will start at 0.0 (completely transparent)
[fader setFromValue:[NSNumber numberWithFloat:startOpacity]];

// And the layer will end at 1.0 (completely opaque)
[fader setToValue:[NSNumber numberWithFloat:endOpacity]];

// MAKE SURE IT DOESN'T CHANGE OPACITY BACK TO STARTING VALUE    
[fader setRemovedOnCompletion:NO];
[fader setFillMode:kCAFillModeForwards];

// Add it to the layer
[boxLayer addAnimation:fader forKey:@"BigFade"];

// SET THE OPACITY TO THE STARTING VALUE
[boxLayer setOpacity:startOpacity];

// Create an animation that will change the position of a layer
CABasicAnimation *mover = [CABasicAnimation animationWithKeyPath:@"position"];

// It will last 1 second and will be delayed by 3 seconds
[mover setDuration:1.0];
[mover setBeginTime:CACurrentMediaTime()+3.0];

// Setting starting position
[mover setFromValue:[NSValue valueWithCGPoint:CGPointMake(startX, startY)]];

// Setting ending position
[mover setToValue:[NSValue valueWithCGPoint:CGPointMake(endX, endY)]];

// MAKE SURE IT DOESN'T MOVE BACK TO STARTING POSITION   
[mover setRemovedOnCompletion:NO];
[mover setFillMode:kCAFillModeForwards];

// Add it to the layer
[boxLayer addAnimation:mover forKey:@"BigMove"];

// SET THE POSITION TO THE STARTING POSITION
[boxLayer setPosition:CGPointMake(startX, startY)];

就个人而言,我认为你在视图上使用基于块的动画更容易完成的工作做了很多工作(为了演示的目的,我假设你的boxLayer是一个CALayer叫做控件的人box).如果你这样做,你也不需要Quartz 2D:

box.alpha = startOpacity;
box.frame = CGRectMake(startX, startY, box.frame.size.width, box.frame.size.height);

[UIView animateWithDuration:1.0
                      delay:3.0
                    options:0
                 animations:^{
                     box.alpha = endOpacity;
                     box.frame = CGRectMake(endX, endY, box.frame.size.width, box.frame.size.height);
                 }
                 completion:nil];