Animate CALayer shadow from square to circle (or rounded corners)

Question

I have a UIImageView, which animates from square to circle with this code:

CABasicAnimation *circleShapeAnimation = [CABasicAnimation animationWithKeyPath:@"cornerRadius"];
circleShapeAnimation.fromValue = [NSNumber numberWithFloat:0.0f];
circleShapeAnimation.toValue = [NSNumber numberWithFloat:cornerRadius];

I also have a separate UIView (its backgroundColor is clearColor), which I use specifically to achieve an animated shadow. Everything animates fine, except the shape animation:

CABasicAnimation* shadowShapeAnimation = [CABasicAnimation animationWithKeyPath: @"shadowPath"];
shadowShapeAnimation.fromValue = (id)[UIBezierPath bezierPathWithRoundedRect: cell.placeImage.bounds cornerRadius:0.0f].CGPath;
shadowShapeAnimation.toValue = (id)[UIBezierPath bezierPathWithRoundedRect: cell.placeImage.bounds cornerRadius:cornerRadius].CGPath;

which, simply put, looks uglier than me with a hangover in the morning.

I would like to achieve a nice, smooth animation of rounded corners. Any idea how to?

score 0 · Answer 1 · edited May 23 '17 at 11:43

The key was to use those methods:

func circlePathWithCenter(center: CGPoint, radius: CGFloat) -> UIBezierPath {
    let circlePath = UIBezierPath()
    circlePath.addArcWithCenter(center, radius: radius, startAngle: -CGFloat(M_PI), endAngle: -CGFloat(M_PI/2), clockwise: true)
    circlePath.addArcWithCenter(center, radius: radius, startAngle: -CGFloat(M_PI/2), endAngle: 0, clockwise: true)
    circlePath.addArcWithCenter(center, radius: radius, startAngle: 0, endAngle: CGFloat(M_PI/2), clockwise: true)
    circlePath.addArcWithCenter(center, radius: radius, startAngle: CGFloat(M_PI/2), endAngle: CGFloat(M_PI), clockwise: true)
    circlePath.closePath()
    return circlePath
}

func squarePathWithCenter(center: CGPoint, side: CGFloat) -> UIBezierPath {
    let squarePath = UIBezierPath()
    let startX = center.x - side / 2
    let startY = center.y - side / 2
    squarePath.moveToPoint(CGPoint(x: startX, y: startY))
    squarePath.addLineToPoint(squarePath.currentPoint)
    squarePath.addLineToPoint(CGPoint(x: startX + side, y: startY))
    squarePath.addLineToPoint(squarePath.currentPoint)
    squarePath.addLineToPoint(CGPoint(x: startX + side, y: startY + side))
    squarePath.addLineToPoint(squarePath.currentPoint)
    squarePath.addLineToPoint(CGPoint(x: startX, y: startY + side))
    squarePath.addLineToPoint(squarePath.currentPoint)
    squarePath.closePath()
    return squarePath
}

Found here: iOS animate/morph shape from circle to square

Animate CALayer shadow from square to circle (or rounded corners)

1 Answers1