渐变层在 iOS 中不起作用

Question

我有制作渐变的代码，但它根本没有显示。如果我改变持有该渐变的视图颜色，我可以看到它。所以视图很好，只是渐变有一些问题。这是我的代码：

class KolodaCardView: UIView {
    var helloWorld = "Hello World"
    var userImage = UIImageView()
    var userName = UILabel()
    var parent = UIView()
    var gradient = CAGradientLayer()
    var gradientView = UIView()

    override init(frame: CGRect) {
        super.init(frame: frame)
        parent = self
        parent.backgroundColor = .clear
        parent.layer.cornerRadius = 16
        parent.clipsToBounds = true

        setupUserImage()
        setupUserName()
    }

    override func layoutSubviews() {
        super.layoutSubviews()
        gradient.frame = gradientView.frame
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    func setupUserImage() {
        parent.addSubview(userImage)
        userImage.snp.makeConstraints { make in
            make.top.equalTo(parent)
            make.bottom.equalTo(parent)
            make.left.equalTo(parent)
            make.right.equalTo(parent)
        }
        userImage.contentMode = .scaleAspectFill
        userImage.clipsToBounds = true
        userImage.layer.cornerRadius = 16

        userImage.addSubview(gradientView)
        gradientView.snp.makeConstraints { (make) in
            make.bottom.equalToSuperview()
            make.left.equalToSuperview()
            make.right.equalToSuperview()
            make.height.equalTo(60)
        }
//        gradientView.backgroundColor = .green
        gradient.startPoint = CGPoint(x: 0, y: 0)
        gradient.endPoint = CGPoint(x: 0, y: 1)
        gradient.locations = [0.5,1.0]
        gradient.frame = gradientView.bounds
        gradient.colors = [UIColor.red.cgColor, UIColor.yellow.cgColor]
        gradient.startPoint = CGPoint(x: 0.0, y: 1.0)
        gradient.endPoint = CGPoint(x: 1.0, y: 1.0)
        gradientView.layer.insertSublayer(gradient, at: 0)
    }

    func setupUserName() {
        parent.addSubview(userName)
        userName.snp.makeConstraints { (make) in
            make.left.equalTo(parent).offset(16)
            make.right.equalTo(parent)
            make.height.equalTo(20)
            make.bottom.equalTo(-20)
        }
        userName.textColor = .black
        userName.textAlignment = .left
    }
}

我在这里检查了几个解决方案，但没有任何效果！有人可以检查一下我是否忽略了某些东西吗？

Answer 1

在 Gradient 中，您必须给出渐变颜色的位置，以填充图层的起点到终点。

gradientLayer.startPoint = CGPoint(x: 0, y: 0)
gradientLayer.endPoint = CGPoint(x: 0, y: 1)
gradientLayer.colors =  [UIColor.red.cgColor ,UIColor.yellow.cgColor]
gradientLayer.locations = [0.5,1.0]
your_gradientView.layer.insertSublayer(gradientLayer, at: 0)