swift - 阴影

官方文档传送门

代码如下：

let testView = UIView(frame: CGRect(x: self.view.frame.width/2 - 100, y: self.view.frame.height/2 - 100, width: 200, height: 200))
        
testView.backgroundColor = .yellow
        
///The opacity of the layer’s shadow. Animatable.
testView.layer.shadowOpacity = 0.5
        
///The color of the layer’s shadow. Animatable.
testView.layer.shadowColor = UIColor.black.cgColor
        
///The offset (in points) of the layer’s shadow. Animatable.
testView.layer.shadowOffset = CGSize(width: 0, height: 0)
        
///The blur radius (in points) used to render the layer’s shadow. Animatable.
testView.layer.shadowRadius = 50

备注：设置了阴影的同时，切记不要设置视图的clipsToBounds为true，否则阴影失效