使用 CAReplicatorLayer
我一直在尝试使用 CAReplicatorlayer、CATextLayer 和非常基本的动画创建很酷的文本效果。我试图让这些字母看起来像是从屏幕顶部掉下来的，后面跟着很酷的复制器，它们会变得越来越不可见。我已经成功做到了这种效果，但并不完全。
到目前为止，这就是我所得到的：
CATextLayer *messageLayer = [CATextLayer layer];
[messageLayer setForegroundColor:[[UIColor blackColor] CGColor]];
[messageLayer setContentsScale:[[UIScreen mainScreen] scale]];
[messageLayer setFrame:CGRectMake(0, 0, 40, 40)];
[messageLayer setString:@"A"];
CAReplicatorLayer *replicatorX = [CAReplicatorLayer layer];
//Set the replicator's attributes
replicatorX.frame = CGRectMake(0, 0, 40, 40);
replicatorX.anchorPoint = CGPointMake(0,0);
replicatorX.position = CGPointMake(0, 0);
replicatorX.instanceCount = 9;
replicatorX.instanceDelay = 0.15;
replicatorX.instanceAlphaOffset = -0.1;
replicatorX.zPosition = 200;
replicatorX.anchorPointZ = -160;
[replicatorX addSublayer:messageLayer];
[self.view.layer addSublayer:replicatorX];
messageLayer.position = CGPointMake(40, 400);
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"position.y"];
animation.fromValue = [NSNumber numberWithInt:0];;
animation.toValue = [NSNumber numberWithInt:400];
animation.duration = 3;
[messageLayer addAnimation:animation forKey:@"s"];
我有两个问题：
- 复制的层从终点开始。
- 当主图层到达最后一个动画点时，动画会停止，并且复制图层无法完成其动画。
I've been trying to create a cool text effect with the CAReplicatorlayer, CATextLayer and very basic animations. I'm trying to make the letters look like they are being droped from the top of the screen followed by cool replicators which will become less and less visible. I've managed to do this effect but not completely.
So far this is what I've got:
CATextLayer *messageLayer = [CATextLayer layer];
[messageLayer setForegroundColor:[[UIColor blackColor] CGColor]];
[messageLayer setContentsScale:[[UIScreen mainScreen] scale]];
[messageLayer setFrame:CGRectMake(0, 0, 40, 40)];
[messageLayer setString:@"A"];
CAReplicatorLayer *replicatorX = [CAReplicatorLayer layer];
//Set the replicator's attributes
replicatorX.frame = CGRectMake(0, 0, 40, 40);
replicatorX.anchorPoint = CGPointMake(0,0);
replicatorX.position = CGPointMake(0, 0);
replicatorX.instanceCount = 9;
replicatorX.instanceDelay = 0.15;
replicatorX.instanceAlphaOffset = -0.1;
replicatorX.zPosition = 200;
replicatorX.anchorPointZ = -160;
[replicatorX addSublayer:messageLayer];
[self.view.layer addSublayer:replicatorX];
messageLayer.position = CGPointMake(40, 400);
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"position.y"];
animation.fromValue = [NSNumber numberWithInt:0];;
animation.toValue = [NSNumber numberWithInt:400];
animation.duration = 3;
[messageLayer addAnimation:animation forKey:@"s"];
I have two problems:
- The replicated layers are starting in the End point.
- When the main layer reach his last animated point the animation stops and the replicated layers can't finish their animation.
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为动画对象的 fillMode 和 returnedOnCompletion 属性设置正确的值有望解决您的问题：
这是由分配给
instanceDelay属性的值引起的，在您的示例中该属性将动画延迟了 0.15 秒。要从 fromValue 呈现动画，您需要通过将动画的 fillMode 设置为 kCAFillModeBackwards 来解决此延迟。发生这种情况是因为默认情况下“动画在完成后会从目标图层的动画中删除。”1。您可以通过将动画属性removedOnCompletion 设置为NO 来覆盖此默认行为。
希望这会有所帮助。
Setting the correct values to the animation object's fillMode and removedOnCompletion properties will hopefully solve your problems:
This is caused by the value assigned to
instanceDelayproperty, which delays the animation with 0.15s in your example. To present the animation from the fromValue, you need to account for this delay by setting the animation's fillMode to kCAFillModeBackwards .This happens because by default "the animation is removed from the target layer's animations upon completion."1. You can override this default behavior by setting the animation attribute removedOnCompletion to NO.
Hope this helps. :)