如何在 view.bounds 上添加 CAGradientLayer 等子层？

Question

如何将我的渐变层作为子层添加到我的视图中，具有相同的大小，我想在其他类中使用它？

我试着用“self.bounds”来做，但没有成功。 如果我给它严格的尺寸，例如： gradientLayer.frame = CGRect(x: 0, y: 0, width: 100, height: 100) - 它会工作，但我需要与我的视图相同的大小。

final class ShimmerLabel: UIView {
    
    private lazy var backShimmerTextLabel: UILabel = {
        let label = UILabel()
        label.text = "Shimmer"
        label.textColor = UIColor(red: 65/255, green: 65/255, blue: 65/255, alpha: 1)
        label.font = UIFont.systemFont(ofSize: 50)
        label.textAlignment = .center
        return label
    }()
    
    private lazy var frontShimmerTextLabel: UILabel = {
        let label = UILabel()
        label.text = "Shimmer"
        label.textColor = .white
        label.font = UIFont.systemFont(ofSize: 50)
        label.textAlignment = .center
        return label
    }()
    
    init() {
        super.init(frame: .zero)
        configureGradientLayer()
        configureLayout()
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    private func configureGradientLayer() {
        
        let gradientLayer = CAGradientLayer()
        gradientLayer.colors = [UIColor.white.cgColor, UIColor.black.cgColor]
        gradientLayer.locations = [0, 1]
        
        gradientLayer.frame = bounds // Dont work with bounds :((
        
        layer.addSublayer(gradientLayer)
    }
    
    private func configureLayout() {
        
        addSubview(backShimmerTextLabel)
        backShimmerTextLabel.snp.makeConstraints { make in
            make.width.height.equalToSuperview()
        }

        addSubview(frontShimmerTextLabel)
        frontShimmerTextLabel.snp.makeConstraints { make in
            make.width.height.equalToSuperview()
        }
    }
}

Answer 1

您可以像这样使用视图的“基础”层作为

CAGradientLayer

：

// use the "base" layer as a gradient layer
lazy var gradientLayer: CAGradientLayer = self.layer as! CAGradientLayer
override class var layerClass: AnyClass {
    return CAGradientLayer.self
}

所以你的班级变成：

final class ShimmerLabel: UIView {
    
    private lazy var backShimmerTextLabel: UILabel = {
        let label = UILabel()
        label.text = "Shimmer"
        label.textColor = UIColor(red: 65/255, green: 65/255, blue: 65/255, alpha: 1)
        label.font = UIFont.systemFont(ofSize: 50)
        label.textAlignment = .center
        return label
    }()
    
    private lazy var frontShimmerTextLabel: UILabel = {
        let label = UILabel()
        label.text = "Shimmer"
        label.textColor = .white
        label.font = UIFont.systemFont(ofSize: 50)
        label.textAlignment = .center
        return label
    }()
    
    // use the "base" layer as a gradient layer
    lazy var gradientLayer: CAGradientLayer = self.layer as! CAGradientLayer
    override class var layerClass: AnyClass {
        return CAGradientLayer.self
    }

    init() {
        super.init(frame: .zero)
        configureGradientLayer()
        configureLayout()
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    private func configureGradientLayer() {
        gradientLayer.colors = [UIColor.white.cgColor, UIColor.black.cgColor]
        gradientLayer.locations = [0, 1]
    }
    
    private func configureLayout() {
        
        addSubview(backShimmerTextLabel)
        backShimmerTextLabel.snp.makeConstraints { make in
            make.width.height.equalToSuperview()
        }
        
        addSubview(frontShimmerTextLabel)
        frontShimmerTextLabel.snp.makeConstraints { make in
            make.width.height.equalToSuperview()
        }
    }
}

渐变将始终填充视图框架。无需添加子层。