How Do You CAKeyframeAnimation Scale? - iphone

Question

I want to create an animation with several key frames. I want my Layer (a button in this case)
to scale up to 1.5 then down to 0.5 then up to 1.2 then down to 0.8 then 1.0.
I also want to EaseIn and EaseOut of each keyframe.
As you can imagine, this will create a Springy/Bounce effect on the spot.
In other parts of my app I have been using CAKeyframeAnimation like this (see below code).
This creates a similar springy animation but for x and y position.
Can I adapt the below code to affect scale instead of position?
Thank you in advance!
- (CAAnimation*)monInAnimation {
CGMutablePathRef path = CGPathCreateMutable();
CGPathMoveToPoint(path,NULL,113,320);
CGPathAddLineToPoint(path, NULL, 113.5, 283);
CGPathAddLineToPoint(path, NULL, 113.5, 179);
CGPathAddLineToPoint(path, NULL, 113.5, 207);
CGPathAddLineToPoint(path, NULL, 113.5, 187);
CGPathAddLineToPoint(path, NULL, 113.5, 199);
CGPathAddLineToPoint(path, NULL, 113.5, 193);
CGPathAddLineToPoint(path, NULL, 113.5, 195);
CGPathAddLineToPoint(path, NULL, 113.5, 194);
CAKeyframeAnimation *
animation = [CAKeyframeAnimation
animationWithKeyPath:#"position"];
[animation setPath:path];
[animation setDuration:1.5];
[animation setCalculationMode:kCAAnimationLinear];
NSArray *arr = [NSArray arrayWithObjects:[NSNumber numberWithFloat:0.0],
[NSNumber numberWithFloat:0.12],
[NSNumber numberWithFloat:0.24],
[NSNumber numberWithFloat:0.36],
[NSNumber numberWithFloat:0.48],
[NSNumber numberWithFloat:0.60],
[NSNumber numberWithFloat:0.72],
[NSNumber numberWithFloat:0.84],
[NSNumber numberWithFloat:1.0],nil];
[animation setKeyTimes:arr];
[animation setTimingFunctions:[NSArray arrayWithObjects:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn],
[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseOut],
[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut],
[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut],
[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut],
[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut],
[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut],
[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut],
[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut], nil]];
//[animation setAutoreverses:YES];
CFRelease(path);
return animation;
}
- (void)monBtnIn {
[monButton.layer setPosition:CGPointMake(113.5,194)];
[monButton.layer addAnimation:[self monInAnimation]
forKey:#"position"];
}

Answer 1

Two alternative solutions for you:
First, You can also animate the transform property.
Using Brad's code, but using #"transform" for the keypath. The primary advantage being that you do not have to calculate the actual frame, but instead provide a simple scaling factor:
Objective-C:
CAKeyframeAnimation *boundsOvershootAnimation = [CAKeyframeAnimation animationWithKeyPath:#"transform"];
CATransform3D startingScale = CATransform3DScale (layer.transform, 0, 0, 0);
CATransform3D overshootScale = CATransform3DScale (layer.transform, 1.2, 1.2, 1.0);
CATransform3D undershootScale = CATransform3DScale (layer.transform, 0.9, 0.9, 1.0);
CATransform3D endingScale = layer.transform;
NSArray *boundsValues = [NSArray arrayWithObjects:[NSValue valueWithCATransform3D:startingScale],
[NSValue valueWithCATransform3D:overshootScale],
[NSValue valueWithCATransform3D:undershootScale],
[NSValue valueWithCATransform3D:endingScale], nil];
[boundsOvershootAnimation setValues:boundsValues];
NSArray *times = [NSArray arrayWithObjects:[NSNumber numberWithFloat:0.0f],
[NSNumber numberWithFloat:0.5f],
[NSNumber numberWithFloat:0.9f],
[NSNumber numberWithFloat:1.0f], nil];
[boundsOvershootAnimation setKeyTimes:times];
NSArray *timingFunctions = [NSArray arrayWithObjects:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseOut],
[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut],
[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut],
nil];
[boundsOvershootAnimation setTimingFunctions:timingFunctions];
boundsOvershootAnimation.fillMode = kCAFillModeForwards;
boundsOvershootAnimation.removedOnCompletion = NO;
Swift 4:
let boundsOvershootAnimation = CAKeyframeAnimation(keyPath: "transform")
let startingScale = CATransform3DScale(layer.transform, 0, 0, 0)
let overshootScale = CATransform3DScale(layer.transform, 1.2, 1.2, 1.0)
let undershootScale = CATransform3DScale(layer.transform, 0.9, 0.9, 1.0)
let endingScale = layer.transform
boundsOvershootAnimation.values = [startingScale, overshootScale, undershootScale, endingScale]
boundsOvershootAnimation.keyTimes = [0.0, 0.5, 0.9, 1.0].map { NSNumber(value: $0) }
boundsOvershootAnimation.timingFunctions = [
CAMediaTimingFunction(name:kCAMediaTimingFunctionEaseOut),
CAMediaTimingFunction(name:kCAMediaTimingFunctionEaseInEaseOut),
CAMediaTimingFunction(name:kCAMediaTimingFunctionEaseInEaseOut)
]
boundsOvershootAnimation.fillMode = kCAFillModeForwards
boundsOvershootAnimation.isRemovedOnCompletion = false
Second, and likely easier, is using FTUtils, an open source wrapper for core animation. It includes a stock "springy" animation.
You can get it at:
http://github.com/neror/ftutils

Answer 2

transform.scale, anyone?
let anim = CAKeyframeAnimation(keyPath: "transform.scale")
anim.values = [0, 1, 0, 1, 0, 1, 0]
anim.duration = 4.0
smallView.layer.addAnimation(anim, forKey: "what")
Totally unrelated, if you are gonna use floats in the values array, you must add them as NSNumbers, otherwise they'd just end up as 0s!
anim.values = [0.0, 1.2, 0.9, 1.0].map { NSNumber(double: $0) }

Answer 3

Rather than setting the path of your CAKeyframeAnimation, you'll want to set the keyframes themselves. I've created a "pop-in" effect before by animating the size of the bounds of a layer:
CAKeyframeAnimation *boundsOvershootAnimation = [CAKeyframeAnimation animationWithKeyPath:#"bounds.size"];
CGSize startingSize = CGSizeZero;
CGSize overshootSize = CGSizeMake(targetSize.width * (1.0f + POPINOVERSHOOTPERCENTAGE), targetSize.height * (1.0f + POPINOVERSHOOTPERCENTAGE));
CGSize undershootSize = CGSizeMake(targetSize.width * (1.0f - POPINOVERSHOOTPERCENTAGE), targetSize.height * (1.0f - POPINOVERSHOOTPERCENTAGE));
NSArray *boundsValues = [NSArray arrayWithObjects:[NSValue valueWithCGSize:startingSize],
[NSValue valueWithCGSize:overshootSize],
[NSValue valueWithCGSize:undershootSize],
[NSValue valueWithCGSize:targetSize], nil];
[boundsOvershootAnimation setValues:boundsValues];
NSArray *times = [NSArray arrayWithObjects:[NSNumber numberWithFloat:0.0f],
[NSNumber numberWithFloat:0.5f],
[NSNumber numberWithFloat:0.9f],
[NSNumber numberWithFloat:1.0f], nil];
[boundsOvershootAnimation setKeyTimes:times];
NSArray *timingFunctions = [NSArray arrayWithObjects:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseOut],
[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut],
[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut],
nil];
[boundsOvershootAnimation setTimingFunctions:timingFunctions];
boundsOvershootAnimation.fillMode = kCAFillModeForwards;
boundsOvershootAnimation.removedOnCompletion = NO;
where POPINOVERSHOOTPERCENTAGE is the fraction by which I wanted to overshoot the target size of the layer.

Answer 4

I don't know if you can use a CAKeyframeAnimation for animating the scale of a UIView, but you can do it with a CABasicAnimation and setting the fromValue and toValue properties, and using that to animate the transform property:
- (CAAnimation*)monInAnimation
{
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:#"transform"];
animation.fromValue = [NSValue valueWithCATransform3D:CATransform3DMakeScale(1.0, 1.0, 1.0)];
animation.toValue = [NSValue valueWithCATransform3D:CATransform3DMakeScale(3.0, 3.0, 3.0)];
[animation setDuration:1.5];
[animation setAutoreverses:YES];
return animation;
}
- (IBAction)monBtnIn
{
[monButton.layer addAnimation:[self monInAnimation] forKey:#"transform"];
}