从正方形到圆形（或圆角）动画 CALayer 阴影答案

【问题标题】：Animate CALayer shadow from square to circle (or rounded corners)从正方形到圆形（或圆角）动画 CALayer 阴影
【发布时间】：2015-08-28 07:01:06
【问题描述】：

我有一个 UIImageView，它使用以下代码从正方形动画到圆形：

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

我还有一个单独的 UIView（它的 backgroundColor 是 clearColor），我专门用它来实现动画阴影。一切都很好，除了形状动画：

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;

简单地说，比我早上宿醉的样子更丑。

我想实现一个漂亮、流畅的圆角动画。知道怎么做吗？

【问题讨论】：

标签： ios objective-c core-animation uibezierpath caanimation

【解决方案1】：

关键是使用这些方法：

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
}

在这里找到：iOS animate/morph shape from circle to square

【讨论】：