未显示CAGradientLayer添加的视图的子视图 [英] Subviews are not displaying for CAGradientLayer added view

问题描述

下面的代码用于为视图添加渐变层.将渐变层添加到视图后，如果我尝试在渐变视图中添加新的子视图，则不会显示新视图

used below code for adding gradient layer for a view. After adding gradient layer to a view if i tried to add new subviews inside my gradient view the new view are not getting displayed

func setGradientBackground(_ view: UIView ,colorStart:CGColor ,colorEnd:CGColor,cornerRadius:CGFloat) {
let gradientLayer = CAGradientLayer()

gradientLayer.colors = [colorStart, colorEnd]
gradientLayer.startPoint = CGPoint(x: 0.0, y: 0.5);
gradientLayer.endPoint = CGPoint(x: 1.0, y: 0.5);

gradientLayer.frame = view.bounds
gradientLayer.cornerRadius = cornerRadius

view.layer.addSublayer(gradientLayer)
}  

如果我使用UIView扩展类，如何直接从情节提要属性检查器设置渐变颜色.我已经在一些库(波斯菊)中看到了这一点，我们可以直接设置评级颜色

if i extend a class with UIView how can i set gradient color directly from storyboard attributes inspector. I have seen this in some libraries (cosmos) where we can directly set rating color

推荐答案

而不是添加渐变图层，而是创建uiview的子类并使用gradientLayer覆盖图层属性

Instead of adding gradient layer, create subclass of uiview and override layer property with gradientLayer

渐变视图:

@IBDesignable class VerticalGradientView: UIView {
    @IBInspectable var topColor: UIColor = UIColor.red {
        didSet {
            setGradient()
        }
    }
    @IBInspectable var bottomColor: UIColor = UIColor.blue {
        didSet {
            setGradient()
        }
    }

    override class var layerClass: AnyClass {
        return CAGradientLayer.self
    }

    override func layoutSubviews() {
        super.layoutSubviews()
        setGradient()
    }

    private func setGradient() {
        (layer as! CAGradientLayer).colors = [topColor.cgColor, bottomColor.cgColor]
        (layer as! CAGradientLayer).startPoint = CGPoint(x: 0.5, y: 0)
        (layer as! CAGradientLayer).endPoint = CGPoint(x: 0.5, y: 1)
    }
}

使用:

let gradientView = VerticalGradientView()
gradientView.frame = CGRect(0,0,100,100)
gradientView.topColor = .black

let label = UILabel()
gradientView.addSubview(label)

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