Question

i’m trying to make a UIView shake when a button is pressed.

I am adapting the code I found on http://www.cimgf.com/2008/02/27/core-animation-tutorial-window-shake-effect/.

However, by trying to adapt the following code to shake a UIView, it does not work:

- (void)animate {
    const int numberOfShakes = 8;
    const float durationOfShake = 0.5f;
    const float vigourOfShake = 0.1f;

    CAKeyframeAnimation *shakeAnimation = [CAKeyframeAnimation animation];

    CGRect frame = lockView.frame;

    CGMutablePathRef shakePath = CGPathCreateMutable();
    CGPathMoveToPoint(shakePath, NULL, CGRectGetMinX(frame), CGRectGetMinY(frame));

    for (int index = 0; index < numberOfShakes; ++index) {
        CGPathAddLineToPoint(shakePath, NULL, CGRectGetMinX(frame) - frame.size.width * vigourOfShake, CGRectGetMinY(frame));

        CGPathAddLineToPoint(shakePath, NULL, CGRectGetMinX(frame) + frame.size.width * vigourOfShake, CGRectGetMinY(frame));
    }

    CGPathCloseSubpath(shakePath);

    shakeAnimation.path = shakePath;
    shakeAnimation.duration = durationOfShake;


    [lockView.layer addAnimation:shakeAnimation forKey:@"frameOrigin"];

}

Answer 1

I wrote that post. It’s overkill for a UIView, plus the parameters are geared toward an OSX app. Do this instead.

CABasicAnimation *animation = 
                         [CABasicAnimation animationWithKeyPath:@"position"];
[animation setDuration:0.05];
[animation setRepeatCount:8];
[animation setAutoreverses:YES];
[animation setFromValue:[NSValue valueWithCGPoint:
               CGPointMake([lockView center].x - 20.0f, [lockView center].y)]];
[animation setToValue:[NSValue valueWithCGPoint:
               CGPointMake([lockView center].x + 20.0f, [lockView center].y)]];
[[lockView layer] addAnimation:animation forKey:@"position"];

You’ll have to play with the duration and repeatCount parameters as well as the x distance from center in the from and to values, but it should give you what you need.

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Swift 3.0

let midX = lockView.center.x
let midY = lockView.center.y

let animation = CABasicAnimation(keyPath: "position")
animation.duration = 0.06
animation.repeatCount = 4
animation.autoreverses = true
animation.fromValue = CGPoint(x: midX - 10, y: midY)
animation.toValue = CGPoint(x: midX + 10, y: midY)
layer.add(animation, forKey: "position")