Button Animate like ios game center button

Question

I am trying to make my buttons animate like buttons in ios game center. they seem to wobble and float about the screen like a bubble. I've tried moving my buttons randomly on the screen, make them move in a constant cirular path at the same time but it's not the same effect.

I need a wobble kind of effect. any ideas are appreciated

Answer 1

Combining a few CAKeyframeAnimations will give you the result. You need one for the position to follow a circle, and one for each scale (x/y) which are timed a bit different to achieve the wobble-effect. Check out the example:

    UIView * view = [[UIView alloc] initWithFrame:CGRectMake(100, 100, 50, 50)];
    view.backgroundColor = [UIColor redColor];
    view.layer.cornerRadius = view.frame.size.width/2;
    [self.view addSubview:view];

    //create an animation to follow a circular path
    CAKeyframeAnimation *pathAnimation = [CAKeyframeAnimation animationWithKeyPath:@"position"];
    //interpolate the movement to be more smooth
    pathAnimation.calculationMode = kCAAnimationPaced;
    //apply transformation at the end of animation (not really needed since it runs forever)
    pathAnimation.fillMode = kCAFillModeForwards;
    pathAnimation.removedOnCompletion = NO;
    //run forever
    pathAnimation.repeatCount = INFINITY;
    //no ease in/out to have the same speed along the path
    pathAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
    pathAnimation.duration = 5.0;

    //The circle to follow will be inside the circleContainer frame.
    //it should be a frame around the center of your view to animate.
    //do not make it to large, a width/height of 3-4 will be enough.
    CGMutablePathRef curvedPath = CGPathCreateMutable();
    CGRect circleContainer = CGRectInset(view.frame, 23, 23);
    CGPathAddEllipseInRect(curvedPath, NULL, circleContainer);

    //add the path to the animation
    pathAnimation.path = curvedPath;
    //release path
    CGPathRelease(curvedPath);
    //add animation to the view's layer
    [view.layer addAnimation:pathAnimation forKey:@"myCircleAnimation"];


    //create an animation to scale the width of the view
    CAKeyframeAnimation *scaleX = [CAKeyframeAnimation animationWithKeyPath:@"transform.scale.x"];
    //set the duration
    scaleX.duration = 1;
    //it starts from scale factor 1, scales to 1.05 and back to 1
    scaleX.values = @[@1.0, @1.05, @1.0];
    //time percentage when the values above will be reached. 
    //i.e. 1.05 will be reached just as half the duration has passed.
    scaleX.keyTimes = @[@0.0, @0.5, @1.0];
    //keep repeating
    scaleX.repeatCount = INFINITY;
    //play animation backwards on repeat (not really needed since it scales back to 1)
    scaleX.autoreverses = YES;
    //ease in/out animation for more natural look
    scaleX.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
    //add the animation to the view's layer
    [view.layer addAnimation:scaleX forKey:@"scaleXAnimation"];

    //create the height-scale animation just like the width one above 
    //but slightly increased duration so they will not animate synchronously
    CAKeyframeAnimation *scaleY = [CAKeyframeAnimation animationWithKeyPath:@"transform.scale.y"];
    scaleY.duration = 1.5;
    scaleY.values = @[@1.0, @1.05, @1.0];
    scaleY.keyTimes = @[@0.0, @0.5, @1.0];
    scaleY.repeatCount = INFINITY;
    scaleY.autoreverses = YES;
    scaleX.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
    [view.layer addAnimation:scaleY forKey:@"scaleYAnimation"];