解决方法
尝试使用CAGradientLayer来实现此目的.我测试过并且工作过.
对于Swift 3.0.
对于Swift 3.0.
let gradient: CAGradientLayer = CAGradientLayer() // put colors into an array,from top to bottom gradient.colors = [UIColor.black.withAlphaComponent(0.5).cgColor,UIColor.clear.cgColor] gradient.frame = view.frame // setting direction and stop points - from top to bottom gradient.startPoint = CGPoint(x: 0,y: 0) gradient.endPoint = CGPoint(x: 0,y: 0.5) yourView.layer.insertSublayer(gradient,at: 0)