how to use CAKeyframeAnimation is for Bouncing effect IOS - ios

Question

I made this code to create CAKeyframeAnimation but result is not bouncing at all
-(CAKeyframeAnimation *)keyframeBounceAnimationFrom:(NSValue *)from
to:(NSValue *)to
forKeypath:(NSString *)keyPath
withDuration:(CFTimeInterval)duration
{
CAKeyframeAnimation * animation = [CAKeyframeAnimation animationWithKeyPath:keyPath];
NSMutableArray * valuesArray = [NSMutableArray array];
NSMutableArray * timeKeyArray = [NSMutableArray array];
[self createBounceFrom:from to:to Values:valuesArray keyTimes:timeKeyArray];
[animation setValues:valuesArray];
[animation setKeyTimes:timeKeyArray];
animation.duration = duration;
return animation;
}
-(void)createBounceFrom:(NSValue *)from to:(NSValue *)to Values:(NSMutableArray *)values keyTimes:(NSMutableArray *)keyTimes
{
CGPoint toPoint= [to CGPointValue];
CGFloat offset = 60;
CGFloat duration = 1.0f;
NSUInteger numberOfOscillations= 4;
[values addObject:from];
[keyTimes addObject:[NSNumber numberWithFloat:0.0f]];
//============
//ideally bouncing will depend from starting position to end poisiton as simulating real Dumping Oscillations
//============
for (NSUInteger index= 0; index <numberOfOscillations ; index++)
{
CGPoint viaPoint = CGPointMake(toPoint.x, toPoint.y + offset);
NSValue * via = [NSValue valueWithCGPoint:viaPoint];
[values addObject:via];
//add time consumed for each oscillation
[keyTimes addObject:[NSNumber numberWithFloat:duration]];
// duration = duration - 0.1;
offset = - offset ;
}
[values addObject:to];
[keyTimes addObject:[NSNumber numberWithFloat:0.6]];
}

Answer 1

Here's a great link with some examples of how to use it:
(After some more looking I found this: http://www.cocoanetics.com/2012/06/lets-bounce/ which I think makes a much better bounce, but more advanced. So wont put the code here)
http://www.touchwonders.com/some-techniques-for-bouncing-animations-in-ios/
The example with CAKeyframeAnimation would be: (taken from the link)
-(void)animateGreenBall
{
NSValue *from = #(greenBall.layer.position.y);
CGFloat bounceDistance = 20.0;
CGFloat direction = (greenUp? 1 : -1);
NSValue *via = #((greenUp ? HEIGHT_DOWN : HEIGHT_UP) + direction*bounceDistance);
NSValue *to = greenUp ? #(HEIGHT_DOWN) : #(HEIGHT_UP);
NSString *keyPath = #"position.y";
CAKeyframeAnimation *animation = [self keyframeBounceAnimationFrom:from
via:via
to:to
forKeyPath:keyPath
withDuration:.6];
[greenBall.layer addAnimation:animation forKey:#"bounce"];
[greenBall.layer setValue:to forKeyPath:keypath];
greenUp = !greenUp;
}
-(CAKeyframeAnimation *)keyframeBounceAnimationFrom:(NSValue *)from
via:(NSValue *)via
to:(NSValue *)to
forKeyPath:(NSString *)keyPath
withDuration:(CFTimeInterval)duration
{
CAKeyframeAnimation *animation = [CAKeyframeAnimation animationWithKeyPath:keyPath];
[animation setValues:#[from, via, to, nil]];
[animation setKeyTimes:#[#(0), #(.7), #(1), nil]];
animation.duration = duration;
return animation;
}