I'm trying to make a circle and animate it. When I click the button, I want to restart this animation from the same StartPoint. When I click the button I should stop, clear the image and start it again.
I'm trying with the code below, but it's not working.
-(IBAction)MakeCircle:(id)sender{
// Make a circular shape
CAShapeLayer *circle = [CAShapeLayer layer];
circle.path = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(0, 0, 2.0*radius, 2.0*radius)
cornerRadius:radius].CGPath;
// Positioning
circle.position = CGPointMake(CGRectGetMidX(self.view.frame)-radius,
CGRectGetMidY(self.view.frame)-radius);
// Configure color and linewidth
circle.fillColor = [UIColor whiteColor].CGColor;
circle.lineWidth = 10;
// Add to parent layer
[self.view.layer addSublayer:circle];
// Configure animation
//CABasicAnimation *drawAnimation = [CABasicAnimation animationWithKeyPath:#"strokeEnd"];
drawAnimation = [CABasicAnimation animationWithKeyPath:#"strokeEnd"];
drawAnimation.duration = 5.0;
drawAnimation.repeatCount = 1.0;
drawAnimation.fromValue = [NSNumber numberWithFloat:0.0f];
drawAnimation.toValue = [NSNumber numberWithFloat:1.0f];
drawAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
// Add the animation
[circle addAnimation:drawAnimation forKey:#"drawCircleAnimation"];
}
//Stop, "clean"screen and start again
-(IBAction)ButtonStopClearStart:(id)sender{
circle.speed = 0.0;
[circle removeAnimationForKey:#"drawCircleAnimation"];
[self MakeCircle:(sender)];
}
Lets say your animation looks something like this...
func runTimerMaskAnimation(duration: CFTimeInterval, fromValue : Double){
...
let path = UIBezierPath(roundedRect: circleBounds, cornerRadius:
circleBounds.size.width * 0.5)
maskLayer?.path = path.reversing().cgPath
maskLayer?.strokeEnd = 0
parentCALayer.mask = maskLayer
let animation = CABasicAnimation(keyPath: "strokeEnd")
animation.duration = duration
animation.fromValue = fromValue
animation.toValue = 0.0
maskLayer?.add(animation!, forKey: "strokeEnd")
}
If I wanted to restart my timer from the original position I would remove the animation, remove the maskLayer and then run the animation again.
maskLayer?.removeAnimation(forKey: "strokeEnd")
maskLayer?.removeFromSuperlayer()
runTimerMaskAnimation(duration: 15, fromValue : 1)
I am trying to animate the the appearance and then the disappearance of a UIBezierPath in a CAShapeLayer.
How I would like to do it is that at start, the path would be invisible by setting strokeStart and strokeEnd to 0. Then, in my animate method I would do a CABasicAnimation with setting the strokeEnd to 1, and after this is done, another animation where I set the strokeStart to 1, so the path would disappear again. Here is what I've tried:
- (void)animate
{
CAShapeLayer *layer = (CAShapeLayer *)self.layer;
CABasicAnimation *appearingAnimation = [CABasicAnimation animationWithKeyPath:#"strokeEnd"];
appearingAnimation.duration = _duration / 2.0;
appearingAnimation.fromValue = #0;
appearingAnimation.toValue = #1;
CABasicAnimation *disappearingAnimation = [CABasicAnimation animationWithKeyPath:#"strokeStart"];
disappearingAnimation.beginTime = _duration / 2.0;
disappearingAnimation.duration = _duration / 2.0;
disappearingAnimation.fromValue = #0;
disappearingAnimation.toValue = #1;
CAAnimationGroup *animationGroup = [CAAnimationGroup animation];
animationGroup.duration = _duration;
animationGroup.animations = #[appearingAnimation, disappearingAnimation];
animationGroup.repeatCount = MAXFLOAT;
[layer addAnimation:animationGroup forKey:#"test"];
}
But the effect I am seeing is that the appearingAnimation is working properly, but as soon as it is done, the path instantly disappears without any animation. After this (_duration/2.0 time later) the whole thing starts over, so it would appear that the disappearingAnimation has no effect.
I tried another approach, but that only worked if the path was on my view.layer. As soon as I added it to a sublayer and tried to animate that one, the second (disappearing) animation had a glitch in it. Here is my second approach:
- (void)animate
{
CAShapeLayer *layer = (CAShapeLayer *)self.layer;
layer.strokeStart = 0;
layer.strokeEnd = 1;
[CATransaction begin];
[CATransaction setCompletionBlock:^{
layer.strokeStart = 1;
layer.strokeEnd = 1;
[CATransaction begin];
[CATransaction setCompletionBlock:^{
[self animate];
}];
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:#"strokeStart"];
animation.duration = _duration / 2.0;
animation.fromValue = [NSNumber numberWithDouble:0];
animation.toValue = [NSNumber numberWithDouble:1];
[layer addAnimation:animation forKey:#"animation1"];
[CATransaction commit];
}];
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:#"strokeEnd"];
animation.duration = _duration / 2.0;
animation.fromValue = [NSNumber numberWithDouble:0];
animation.toValue = [NSNumber numberWithDouble:1];
[layer addAnimation:animation forKey:#"animation"];
[CATransaction commit];
}
Any idea why the first solution doesn't work at all, or why the second is only working properly on the view.layer and not on a sublayer?
When animating a layer property, you will want to set the layer property to the end value before adding the animation, as the animation changes are only applied to the presentation, not the model layer. Once the animation is completed it will be removed, leaving the layer in the state it was before.
Both the first and second methods you have outlined worked for me once a layer had been created (missing from your snippet):
- (void)animate
{
CAShapeLayer *layer = [CAShapeLayer layer];
CGFloat _duration = 2.0;
CGFloat radius = self.view.frame.size.width/2.0;
CGFloat startAngle = -(M_PI_2);
CGFloat endAngle = (3*M_PI_2);
CGPoint center = CGPointMake(self.view.frame.size.width/2.0, self.view.frame.size.height/2.0);
layer.path = [[UIBezierPath bezierPathWithArcCenter:center
radius:radius
startAngle:startAngle
endAngle:endAngle
clockwise:YES] CGPath];
layer.fillColor = [[UIColor clearColor] CGColor];
layer.strokeColor = [[UIColor blackColor] CGColor];
[self.view.layer addSublayer:layer];
... {animation code}
}
I think it is the problem of the value of _duration / 2.0. It may be the problem of floating number calculation.
Try not to halve the total duration but to make the durations of appearingAnimation and disappearingAnimation as the base duration:
#define DURATION_BASE 1
// You can choose the DURATION_BASE value whaterver you like
- (void)animate
{
CAShapeLayer *layer = (CAShapeLayer *)self.layer;
CABasicAnimation *appearingAnimation = [CABasicAnimation animationWithKeyPath:#"strokeEnd"];
appearingAnimation.duration = DURATION_BASE;
appearingAnimation.fromValue = #0;
appearingAnimation.toValue = #1;
CABasicAnimation *disappearingAnimation = [CABasicAnimation animationWithKeyPath:#"strokeStart"];
disappearingAnimation.beginTime = appearingAnimation.duration;
disappearingAnimation.duration = DURATION_BASE;
disappearingAnimation.fromValue = #0;
disappearingAnimation.toValue = #1;
CAAnimationGroup *animationGroup = [CAAnimationGroup animation];
animationGroup.duration = appearingAnimation.duration+disappearingAnimation.duration;
animationGroup.animations = #[appearingAnimation, disappearingAnimation];
animationGroup.repeatCount = MAXFLOAT;
[layer addAnimation:animationGroup forKey:#"test"];
}
When you want to change durations of appearingAnimation and disappearingAnimation, you just need modify the code like
appearingAnimation.duration = DURATION_BASE*1.2;
disappearingAnimation.duration = DURATION_BASE*1.2;
I'm trying to create a circular bar such the one that you can find around the recording button in the native camera on iOS when you are doing a timelapse.
A circle is created along the animation, and once it is completed is removed again "naturally".
I tried next code:
CAShapeLayer *circle = [CAShapeLayer layer];
circle.path = [UIBezierPath bezierPathWithArcCenter:CGPointMake(self.lapseBtnOutlet.center.x, self.lapseBtnOutlet.center.y) radius:28 startAngle:2*M_PI*0-M_PI_2 endAngle:2*M_PI*1-M_PI_2 clockwise:YES].CGPath;
circle.fillColor = [UIColor clearColor].CGColor;
circle.strokeColor = [UIColor whiteColor].CGColor;
circle.lineWidth = 2.0;
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:#"strokeEnd"];
animation.duration = self.lapseInterval;
animation.removedOnCompletion = NO;
animation.fromValue = #(0);
animation.toValue = #(1);
animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
[circle addAnimation:animation forKey:#"drawCircleAnimation"];
But my problem now is that I don't know how to "remove" the line from start-to-end.
I tried with autoreverse property, but it removes the circle from end-to-start instead from start-to-end. Any ideas?
You need to animate the strokeStart from 0 to 1, and when the animation finishes, remove the shape layer.
- (void)viewDidLoad {
[super viewDidLoad];
[self performSelector:#selector(animateProperty:) withObject:#"strokeEnd" afterDelay:1];
[self performSelector:#selector(animateProperty:) withObject:#"strokeStart" afterDelay:3];
}
-(void)animateProperty:(NSString *) prop {
if (! self.circle) {
self.circle = [CAShapeLayer layer];
self.circle.path = [UIBezierPath bezierPathWithArcCenter:CGPointMake(self.lapseBtnOutlet.center.x, self.lapseBtnOutlet.center.y) radius:28 startAngle:2*M_PI*0-M_PI_2 endAngle:2*M_PI*1-M_PI_2 clockwise:YES].CGPath;
self.circle.fillColor = [UIColor clearColor].CGColor;
self.circle.strokeColor = [UIColor whiteColor].CGColor;
self.circle.lineWidth = 2.0;
[self.view.layer addSublayer:self.circle];
}
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:prop];
animation.delegate = ([prop isEqualToString:#"strokeStart"])? self : nil;
animation.duration = 1;
animation.removedOnCompletion = NO;
animation.fromValue = #0;
animation.toValue = #1;
[self.circle addAnimation:animation forKey:prop];
}
-(void)animationDidStop:(CAAnimation *)anim finished:(BOOL)flag {
[self.circle removeFromSuperlayer];
self.circle = nil;
}
I have a circle that I animate growing outwards and getting bigger. Unfortunately despite me setting the anchorPoint it doesnt animate from the center outwards, it seems to lock position top left. What is going on?
See this image that depicts the circles off center
Code
- (void)setLayerProperties {
rippleLayer = [[CAShapeLayer alloc] init];
rippleLayer.fillColor = [UIColor clearColor].CGColor;
rippleLayer.strokeColor = _Color.CGColor;
//rippleLayer.contentsGravity = #"center";
rippleLayer.anchorPoint = CGPointMake(0.5,0.5);
rippleLayer.bounds = self.bounds;
rippleLayer.path = bezierPath.CGPath;
[self.layer addSublayer:rippleLayer];
}
// Now animate the circle outwards
rippleLayer.opacity = 1;
CABasicAnimation *scale = [CABasicAnimation animationWithKeyPath:#"transform.scale"];
[scale setFromValue:[NSNumber numberWithFloat:1.0f]];
[scale setToValue:[NSNumber numberWithFloat:2.0f]];
[scale setRepeatCount:1];
[scale setDuration:1.0f];
//[scale setRemovedOnCompletion:YES];
[scale setFillMode:kCAFillModeForwards];
[rippleLayer addAnimation:scale forKey:scale.keyPath];
To scale layer at it's center, you need to set layer's position.This may help you
I want to draw a Smooth animations in iOS using CAPropertyAnimations
define RADIANS(angle) ((angle) / 180.0 * M_PI)
CGPoint testCenter = CGPointMake(144.5, 230.0);
CAShapeLayer *aTestLayer = [CAShapeLayer layer];
aTestLayer.path = [UIBezierPath bezierPathWithArcCenter:**CGPointZero** radius:15.0 startAngle:RADIANS(0) endAngle:RADIANS(360) clockwise:YES].CGPath;
aTestLayer.fillColor = [UIColor clearColor].CGColor;
aTestLayer.strokeColor = [UIColor whiteColor].CGColor;
**aTestLayer.position = testCenter;**
aTestLayer.borderWidth = 2.0;
[self.view.layer addSublayer:aTestLayer];
CABasicAnimation *pulse = [CABasicAnimation animationWithKeyPath:#"transform.scale"];
pulse.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseOut];
pulse.duration = 2;
pulse.repeatCount = HUGE_VALF;
pulse.autoreverses = YES;
pulse.fromValue = [NSNumber numberWithFloat:1.0];
pulse.toValue = [NSNumber numberWithFloat:2.0];
[aTestLayer addAnimation:pulse forKey:nil];
I'm attempting to create a fairly simple CoreAnimation for use in an AVComposition. My goal is to create a CALayer which, through various sublayers, fades a title in and out, then fades in an out images. A slideshow, basically. This is being exported to a .mov using AVAssetWriter.
With help from the WWDC 2011 AVEditDemo, I've been able to get a title and images appearing. The problem is that they are all on screen at the same time!
I have created each layer with an opacity of 0.0. I have then added an CABasicAnimation to fade them from 0.0 to 1.0, using the following code:
CABasicAnimation *fadeInAnimation = [CABasicAnimation animationWithKeyPath:#"opacity"];
fadeInAnimation.fromValue = [NSNumber numberWithFloat:0.0];
fadeInAnimation.toValue = [NSNumber numberWithFloat:1.0];
fadeInAnimation.additive = NO;
fadeInAnimation.removedOnCompletion = YES;
fadeInAnimation.beginTime = 1.0;
fadeInAnimation.duration = 1.0;
fadeInAnimation.fillMode = kCAFillModeForwards;
[titleLayer addAnimation:fadeInAnimation forKey:nil];
The problem seems to be the 'beginTime' property. The "1.0" is meant to be a delay, so it starts 1 second after the start of the animation. However, it is appearing on the screen straight away. A fade out animation
The reverse of this code, for the fade out, simply changes the fromValue to 1.0 and the toValue to 0.0. It has a begin time of 4.0 and works perfectly.
I'm using the following to create the animatedTitleLayer:
CATextLayer *titleLayer = [CATextLayer layer];
titleLayer.string =self.album.title;
titleLayer.font = #"Helvetica";
titleLayer.fontSize = videoSize.height / 6;
titleLayer.alignmentMode = kCAAlignmentCenter;
titleLayer.bounds = CGRectMake(0, 0, videoSize.width, videoSize.height / 6);
titleLayer.foregroundColor = [[UIColor redColor]CGColor];
titleLayer.opacity = 0.0;
The image fade in animations have a beginTime 5 seconds apart. Like the title, their fade out animations work fine.
Any help would be greatly appreciated!
Cheers!
EDIT
The answers were all helpful, but ultimately I discovered that only one animation could be added to a CALayer. The fade out animation was working as it was the last one added.
I then tried a CAAnimationGroup, but this didn't work as I was modifying the same key value path.
So I've realised that a CAKeyframeAnimation is the best for this. Only I'm having some difficulty with that too! The code is now fading in okay, but it isn't fading out. I've tried various fillMode's, changed the duration, etc. Can't make it work!!
Here is my code:
CAKeyframeAnimation *fadeInAndOut = [CAKeyframeAnimation animationWithKeyPath:#"opacity"];
fadeInAndOut.duration = 5.0;
fadeInAndOut.autoreverses = NO;
fadeInAndOut.keyTimes = [NSArray arrayWithObjects: [NSNumber numberWithFloat:0.0],
[NSNumber numberWithFloat:1.0],
[NSNumber numberWithFloat:4.0],
[NSNumber numberWithFloat:5.0], nil];
fadeInAndOut.values = [NSArray arrayWithObjects: [NSNumber numberWithFloat:0.0],
[NSNumber numberWithFloat:1.0],
[NSNumber numberWithFloat:1.0],
[NSNumber numberWithFloat:0.0], nil];
fadeInAndOut.beginTime = 1.0;
fadeInAndOut.removedOnCompletion = NO;
fadeInAndOut.fillMode = kCAFillModeBoth;
[titleLayer addAnimation:fadeInAndOut forKey:nil];
I'm faced the same issue and the problem is - one layer can't contain fade in and out.
So you can add the other animation to the parent layer as i did
CALayer *parentLayer = [CALayer layer];
CALayer *animtingLayer = [CALayer layer];
//FADE IN
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:#"opacity"];
animation.beginTime = CMTimeGetSeconds(img.startTime);
animation.duration = CMTimeGetSeconds(_timeline.transitionDuration);
animation.fromValue = [NSNumber numberWithFloat:0.0f];
animation.toValue = [NSNumber numberWithFloat:1.0f];
animation.removedOnCompletion = NO;
animation.fillMode = kCAFillModeBoth;
animation.additive = NO;
[parentLayer addAnimation:animation forKey:#"opacityIN"];
//FADE OUT
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:#"opacity"];
animation.beginTime = CMTimeGetSeconds(CMTimeAdd(img.passTimeRange.start, img.passTimeRange.duration));
animation.duration = CMTimeGetSeconds(_timeline.transitionDuration);
animation.fromValue = [NSNumber numberWithFloat:1.0f];
animation.toValue = [NSNumber numberWithFloat:0.0f];
animation.removedOnCompletion = NO;
animation.fillMode = kCAFillModeBoth;
animation.additive = NO;
[animtingLayer addAnimation:animation forKey:#"opacityOUT"];
[parentLayer addSublayer:animtingLayer];
Man, so many complicated answers. The simplest way is just to add autoreverse. Voila.
CABasicAnimation *fadeInAndOut = [CABasicAnimation animationWithKeyPath:#"opacity"];
fadeInAndOut.duration = 5.0;
fadeInAndOut.autoreverses = YES;
fadeInAndOut.fromValue = [NSNumber numberWithFloat:0.0];
fadeInAndOut.toValue = [NSNumber numberWithFloat:1.0];
fadeInAndOut.repeatCount = HUGE_VALF;
fadeInAndOut.fillMode = kCAFillModeBoth;
[titleLayer addAnimation:fadeInAndOut forKey:#"myanimation"];
This works for me:
let fadeAnimation = CAKeyframeAnimation(keyPath:"opacity")
fadeAnimation.beginTime = AVCoreAnimationBeginTimeAtZero + start
fadeAnimation.duration = duration
fadeAnimation.keyTimes = [0, 1/8.0, 5/8.0, 1]
fadeAnimation.values = [0.0, 1.0, 1.0, 0.0]
fadeAnimation.removedOnCompletion = false
fadeAnimation.fillMode = kCAFillModeForwards
layer.addAnimation(fadeAnimation, forKey:"animateOpacity")
layer.opacity = 0.0
Try:
fadeInAnimation.beginTime = CACurrentMediaTime()+1.0;
Borrowing from the link mentioned by gamblor87 and adding my comments as explanation.
//create a fadeInOut CAKeyframeAnimation on opacticy
CAKeyframeAnimation *fadeInAndOut = [CAKeyframeAnimation animationWithKeyPath:#"opacity"];
//set duration
fadeInAndOut.duration = 5.0;
//autoreverses defaults to NO so we don't need this.
//fadeInAndOut.autoreverses = NO;
//keyTimes are time points on duration timeline as a fraction of animation duration (here 5 seconds).
fadeInAndOut.keyTimes = [NSArray arrayWithObjects:[NSNumber numberWithFloat:0.0],
[NSNumber numberWithFloat:0.20],
[NSNumber numberWithFloat:0.80],
[NSNumber numberWithFloat:1.0], nil];
//set opacity values at various points during the 5second animation
fadeInAndOut.values = [NSArray arrayWithObjects:[NSNumber numberWithFloat:0.0],//opacity 0 at 0s (corresponds to keyTime = 0s/5s)
[NSNumber numberWithFloat:1.0],//opacity 1 at 1s (corresponds to keyTime = 1s/5s)
[NSNumber numberWithFloat:1.0],//opacity 1 upto 4s (corresponds to keyTime = 4s/5s)
[NSNumber numberWithFloat:0.0],//opacity 0 at 5s (corresponds to keyTime = 5s/5s)
nil];
//delay in start of animation. What we are essentially saying is to start the 5second animation after 1second.
fadeInAndOut.beginTime = 1.0;
//don't remove the animation on completion.
fadeInAndOut.removedOnCompletion = NO;
//fill mode. In most cases we won't need this.
fadeInAndOut.fillMode = kCAFillModeBoth;
//add the animation to layer
[titleLayer addAnimation:fadeInAndOut forKey:nil];
The point is key name. You have to set the opacity key.
layer.add(animation, forKey: nil) // Not Working
layer.add(animation, forKey: "opacity") // Working
Check the sample code. I tested in Swift 4
let animation = CAKeyframeAnimation()
animation.duration = 1.53
animation.autoreverses = false
animation.keyTimes = [0, 0.51, 0.85, 1.0]
animation.values = [0.5, 0.5, 1.0, 0.5]
animation.beginTime = 0
animation.isRemovedOnCompletion = false
animation.fillMode = kCAFillModeBoth
animation.repeatCount = .greatestFiniteMagnitude
layer.add(animation, forKey: "opacity")
The core of the problem was not understanding the keyTimes property of a CAKeyframeAnimation. This question clarified it all and set me down the right path:
What kind of value is keyTime in an CAKeyFrameAnimation?
LenK's answer worked perfectly for me. If anyone is interested, I re-wrote for Obj-C (note I also slightly changed the key frames on fade in):
CAKeyframeAnimation *fadeInAndOutAnimation = [CAKeyframeAnimation animationWithKeyPath:#"opacity"];
fadeInAndOutAnimation.beginTime = CACurrentMediaTime() + beginTime;
fadeInAndOutAnimation.duration = duration;
fadeInAndOutAnimation.keyTimes = #[#0.0, #( 2.0 / 8.0 ), #( 5.0 / 8.0 ), #1.0];
fadeInAndOutAnimation.values = #[#0.0, #1.0, #1.0, #0.0];
fadeInAndOutAnimation.removedOnCompletion = false;
fadeInAndOutAnimation.fillMode = kCAFillModeForwards;
Look at my answer https://stackoverflow.com/a/44204846/667483
In summary: to use beginTime you should set fillMode to kCAFillModeBackwards on you animation object.
The alternative way is the using CAAnimationGroup. CAKeyframeAnimation also works fine for UI. This code works fine in UI for show animation real-time. But will not work at all in AVVideoCompositionCoreAnimationTool - please scroll down if you need it. It is not code ready for copy-paste but you can get the idea. Also, you can add addition animations to the group:
for (HKAnimatedLayer *animLayer in layersList) {
overlayLayer = [CALayer layer];
[overlayLayer setContents:(id)[animLayer.image CGImage]];
overlayLayer.frame = CGRectMake(0, 0, size.width, size.height);
[overlayLayer setMasksToBounds:YES];
NSMutableArray *animations = [NSMutableArray array];
// Step 1
{
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:#"opacity"];
animation.toValue = #(0);
animation.duration = kLayerFadeDuration;
animation.beginTime = kMovieDuration/5;
animation.fillMode = kCAFillModeForwards;
[animations addObject:animation];
}
{
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:#"opacity"];
animation.toValue = #(1.0);
animation.duration = kLayerFadeDuration;
animation.beginTime = kMovieDuration*2/3;
animation.fillMode = kCAFillModeForwards;
[animations addObject:animation];
}
CAAnimationGroup *animationGroup = [CAAnimationGroup animation];
animationGroup.animations = animations;
animationGroup.duration = kMovieDuration;
animationGroup.fillMode = kCAFillModeForwards;
animationGroup.removedOnCompletion = YES;
[overlayLayer addAnimation:animationGroup forKey:nil];
[parentLayer addSublayer:overlayLayer];
}
Here small note about animation on layers for AVVideoCompositionCoreAnimationTool. You can see relevant gif image (titles should appear and disappear one by one). To solve this issue I use 2 separate CALayer's because for some reason on one layer 2 opaque animations on multiple layers are glitched.
// set up the parent layer
CALayer *parentLayer = [CALayer layer];
parentLayer.frame = CGRectMake(0, 0, size.width, size.height);
// one layer for one animation
CALayer *overlayLayer, *barrierLayer;
CABasicAnimation *animation;
for (HKAnimatedLayer *animLayer in layersList) {
overlayLayer = [CALayer layer];
overlayLayer.contents = (id)[animLayer.image CGImage];
overlayLayer.frame = CGRectMake(0, 0, size.width, size.height);
overlayLayer.masksToBounds = YES;
// layer with appear animation
if (animLayer.fromTime != 0 && (animLayer.fromTime - kLayerFadeDuration)>0) {
overlayLayer.opacity = 0.0;
animation = [CABasicAnimation animationWithKeyPath:#"opacity"];
animation.fromValue = #(0);
animation.toValue = #(1);
animation.additive = NO;
animation.removedOnCompletion = NO;
animation.beginTime = animLayer.fromTime - kLayerFadeDuration;
animation.duration = kLayerFadeDuration;
animation.fillMode = kCAFillModeForwards;
[overlayLayer addAnimation:animation forKey:#"fadeIn"];
}
if (animLayer.toTime == kMovieDuration) {
[parentLayer addSublayer:overlayLayer];
} else { // layer with dissappear animation
barrierLayer = [CALayer layer];
barrierLayer.frame = CGRectMake(0, 0, size.width, size.height);
barrierLayer.masksToBounds = YES;
[barrierLayer addSublayer:overlayLayer];
animation = [CABasicAnimation animationWithKeyPath:#"opacity"];
animation.fromValue = #(1);
animation.toValue = #(0);
animation.additive = NO;
animation.removedOnCompletion = NO;
animation.beginTime = animLayer.toTime;
animation.duration = kLayerFadeDuration;
animation.fillMode = kCAFillModeForwards;
[overlayLayer addAnimation:animation forKey:#"fadeOut"];
[parentLayer addSublayer:barrierLayer];
}
}
And at the end, we can get proper animation sequence