How do you create a wiggle animation similar to ip

Question

We are currently developing an application that contains a series of icons. We want the icons to wiggle like the app deletion animations when pressed. What would be the best way to code this animation sequence?

Answer 1

Looking at the iOS implementation a bit closer, there are two things that make theirs a bit more realistic than the code mentioned here:

• The icons appear to have a bounce as well as a rotation
• Every icon has its own timing -- they are not all synchronized

I based myself on the answers here (and with some help from this answer) to add the rotation, the bounce and a bit of randomness to the duration of each animation.

#define kWiggleBounceY 4.0f
#define kWiggleBounceDuration 0.12
#define kWiggleBounceDurationVariance 0.025

#define kWiggleRotateAngle 0.06f
#define kWiggleRotateDuration 0.1
#define kWiggleRotateDurationVariance 0.025

-(void)startWiggling {
    [UIView animateWithDuration:0
                     animations:^{
                         [self.layer addAnimation:[self rotationAnimation] forKey:@"rotation"];
                         [self.layer addAnimation:[self bounceAnimation] forKey:@"bounce"];
                         self.transform = CGAffineTransformIdentity;
                     }];
}

-(CAAnimation*)rotationAnimation {
    CAKeyframeAnimation* animation = [CAKeyframeAnimation animationWithKeyPath:@"transform.rotation.z"];
    animation.values = @[@(-kWiggleRotateAngle), @(kWiggleRotateAngle)];

    animation.autoreverses = YES;
    animation.duration = [self randomizeInterval:kWiggleRotateDuration
                                    withVariance:kWiggleRotateDurationVariance];
    animation.repeatCount = HUGE_VALF;

    return animation;
}

-(CAAnimation*)bounceAnimation {
    CAKeyframeAnimation* animation = [CAKeyframeAnimation animationWithKeyPath:@"transform.translation.y"];
    animation.values = @[@(kWiggleBounceY), @(0.0)];

    animation.autoreverses = YES;
    animation.duration = [self randomizeInterval:kWiggleBounceDuration
                                    withVariance:kWiggleBounceDurationVariance];
    animation.repeatCount = HUGE_VALF;

    return animation;
}

-(NSTimeInterval)randomizeInterval:(NSTimeInterval)interval withVariance:(double)variance {
    double random = (arc4random_uniform(1000) - 500.0) / 500.0;
    return interval + variance * random;
}

I implemented this code on a UICollectionView which had 30 items bouncing and the performance was flawless on an iPad 2.

Answer 2

    func startWiggling() {
        deleteButton.isHidden = false
        guard contentView.layer.animation(forKey: "wiggle") == nil else { return }
        guard contentView.layer.animation(forKey: "bounce") == nil else { return }

        let angle = 0.04

        let wiggle = CAKeyframeAnimation(keyPath: "transform.rotation.z")
        wiggle.values = [-angle, angle]
        wiggle.autoreverses = true
        wiggle.duration = randomInterval(0.1, variance: 0.025)
        wiggle.repeatCount = Float.infinity
        contentView.layer.add(wiggle, forKey: "wiggle")

        let bounce = CAKeyframeAnimation(keyPath: "transform.translation.y")
        bounce.values = [4.0, 0.0]
        bounce.autoreverses = true
        bounce.duration = randomInterval(0.12, variance: 0.025)
        bounce.repeatCount = Float.infinity
        contentView.layer.add(bounce, forKey: "bounce")
    }

    func stopWiggling() {
        deleteButton.isHidden = true
        contentView.layer.removeAllAnimations()
        }

    func randomInterval(_ interval: TimeInterval, variance: Double) -> TimeInterval {
        return interval + variance * Double((Double(arc4random_uniform(1000)) - 500.0) / 500.0)
    }

Look at this iOS SpingBoard example