How to chain different CAAnimation in an iOS appli

问题:

I need to chain animations, CABasicAnimation or CAAnimationGroup but I don't know how to do it, the only that I do is that all the animation execute at the same time for the same layer.

How could I do it?

For example, a layer with its contents set to a car image:

1st: move X points to right

2nd: Rotate 90ª to left

3rd: Move X point

4th: Scale the layer

All this animations must be executed in a secuencial way, but I can't do it :S

BTW: I am not english, sorry if I made some mistakes in my grammar :D

回答1:

tl;dr: You need to manually add each animation after the previous finishes.

---

There is no built in way to add sequential animations. You could set the delay of each animation to be the sum of all previous animations but I wouldn't recommend it.

Instead I would create all the animations and add them to a mutable array (using the array as a queue) in the order they are supposed to run. Then by setting yourself as the animations delegate to all the animations you can get the animationDidStop:finished: callback whenever an animation finishes.

In that method you will remove the first animation (meaning the next animation) from the array and add it to the layer. Since you are the delegate you will get a second animation when that one finishes in which case the animationDidStop:finished: callback will run again and the next animation is removed from the mutable array and added to the layer.

Once the array of animations is empty, all animations will have run.

---

Some sample code to get you started. First you set up all your animations:

CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"backgroundColor"];
[animation setToValue:(id)[[UIColor redColor] CGColor]];
[animation setDuration:1.5];
[animation setDelegate:self];
[animation setValue:[view layer] forKey:@"layerToApplyAnimationTo"];

// Configure other animations the same way ...

[self setSequenceOfAnimations:[NSMutableArray arrayWithArray: @[ animation, animation1, animation2, animation3, animation4, animation5 ] ]];

// Start the chain of animations by adding the "next" (the first) animation
[self applyNextAnimation];

Then in the delegate callback you simply apply the next animation again

- (void)animationDidStop:(CAAnimation *)animation finished:(BOOL)finished {
    [self applyNextAnimation];
}

- (void)applyNextAnimation {
     // Finish when there are no more animations to run
    if ([[self sequenceOfAnimations] count] == 0) return;

    // Get the next animation and remove it from the "queue"
    CAPropertyAnimation * nextAnimation = [[self sequenceOfAnimations] objectAtIndex:0];
    [[self sequenceOfAnimations] removeObjectAtIndex:0];

    // Get the layer and apply the animation
    CALayer *layerToAnimate = [nextAnimation valueForKey:@"layerToApplyAnimationTo"];
    [layerToAnimate addAnimation:nextAnimation forKey:nil];
}

I'm using a custom key layerToApplyAnimationTo so that each animation knows its layer (it works just by setValue:forKey: and valueForKey:).

回答2:

What david suggests works fine, but I would recommend a different way.

If all your animations are to the same layer, you can create an animation group, and make each animation have a different beginTime, where the first animation starts at beginTime 0, and each new animation starts after the total duration of the animations before.

If your animations are on different layers, though, you can't use animation groups (all the animations in an animation group must act on the same layer.) In that case, you need to submit separate animations, each of which has a beginTime that is offset from CACurrentMediaTime(), e.g.:

CGFloat totalDuration = 0;
CABasicAnimation *animationOne = [CABasicAnimation animationWithKeyPath: @"alpha"];
animationOne.beginTime = CACurrentMediaTime(); //Start instantly.
animationOne.duration = animationOneDuration;
...
//add animation to layer

totalDuration += animationOneDuration;

CABasicAnimation *animationTwo = [CABasicAnimation animationWithKeyPath: @"position"];
animationTwo.beginTime = CACurrentMediaTime() + totalDuration; //Start after animation one.
animationTwo.duration = animationTwoDuration;
...
//add animation to layer

totalDuration += animationTwoDuration;


CABasicAnimation *animationThree = [CABasicAnimation animationWithKeyPath: @"position"];
animationThree.beginTime = CACurrentMediaTime() + totalDuration; //Start after animation three.
animationThree.duration = animationThreeDuration;
...
//add animation to layer

totalDuration += animationThreeDuration;

回答3:

Here's a solution in Swift:

var animations = [CABasicAnimation]()

var animation1 = CABasicAnimation(keyPath: "key_path_1")
// animation set up here, I've included a few properties as an example
animation1.duration = 1.0
animation1.fromValue = 1
animation1.toValue = 0
animation1.append(animation1)

var animation2 = CABasicAnimation(keyPath: "key_path_2")
animation2.duration = 1.0
animation2.fromValue = 1
animation2.toValue = 0
// setting beginTime is the key to chaining these
animation2.beginTime = 1.0
animations.append(animation2)

let group = CAAnimationGroup()
group.duration = 2.0
group.repeatCount = FLT_MAX
group.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)
group.animations = animations

yourLayer.addAnimation(group, forKey: nil)

回答4:

Either David's approach or the beginTime property are ok for chaining animations. See http://wangling.me/2011/06/time-warp-in-animation.html - it clarifies the use of beginTime and other CAMediaTiming protocol properties.

回答5:

Use KVC. setValue for Key for every animation. After that in animationDidStop you can define what animation has been stopped and run next in chain.

- (void)moveXrightAnimation {
    CABasicAnimation* theAnimation = ...
    [theAnimation setValue:@"movexright" forKey:@"animationID"];
//animation
}

- (void)rotate90leftAnimation {
    CABasicAnimation* theAnimation = ...
    [theAnimation setValue:@"rotate90left" forKey:@"animationID"];
//animation
}

- (void)moveXpointAnimation {
    CABasicAnimation* theAnimation = ...
    [theAnimation setValue:@"movexpoint" forKey:@"animationID"];
//animation
}

- (void)scaleAnimation {
    CABasicAnimation* theAnimation = ...
    [theAnimation setValue:@"scale" forKey:@"animationID"];
//animation
}

#pragma mark - CAAnimationDelegate

- (void)animationDidStop:(CAAnimation *)anim finished:(BOOL)flag {
    
    if([[anim valueForKey:@"animationID"] isEqual:@"movexright"]) {
        [self rotate90leftAnimation];
    }
    if([[anim valueForKey:@"animationID"] isEqual:@"rotate90left"]) {
        [self moveXpointAnimation];
    }
    if([[anim valueForKey:@"animationID"] isEqual:@"movexpoint"]) {
        [self scaleAnimation];
    }
}