UIView 漸變不改變 colors 當按鈕被點擊

Question

當用戶點擊一個按鈕時，它會隨機化 colors 用於在大圓圈中創建漸變。 下面是兩個小圓圈，顯示用於漸變的實心 colors。 它們在開始時都正確顯示（主圓圈是隨機小圓圈顏色的漸變）但是當我點擊按鈕時，只有小圓圈改變顏色； 大圓圈保持相同的梯度 colors。

擴展和查看 Controller：

extension UIView {
func setupGradientBackground(colorOne: UIColor, colorTwo: UIColor) {
        let gradientLayer: CAGradientLayer = CAGradientLayer()
        gradientLayer.colors = [colorOne.cgColor, colorTwo.cgColor]
        gradientLayer.locations = [0.0, 1.0]
        gradientLayer.startPoint = CGPoint(x: 0.0, y: 1.0)
        gradientLayer.endPoint = CGPoint(x: 1.0, y: 0.0)
        gradientLayer.frame = self.bounds

        self.layer.insertSublayer(gradientLayer, at: 0)
    }
}

extension UIColor {
     static var random: UIColor {
        return UIColor(red: .random(in: 0...1), green: .random(in: 0...1), blue: .random(in: 0...1), alpha: 1.0)
    }
}

class GradientController: UIViewController {
    let gradientView = GradientView()
    let leftGradientColor: UIColor = .random
    let rightGradientColor: UIColor = .random
}

    override func viewDidLoad() {
        super.viewDidLoad()
        view = gradientView
        newGradient()
    }

    func newGradient() {
        gradientView.mainCircleView.setupGradientBackground(colorOne: leftGradientColor, colorTwo: rightGradientColor)
        gradientView.colorCircleLeftView.backgroundColor = leftGradientColor
        gradientView.colorCircleRightView.backgroundColor = rightGradientColor
        gradientView.gradientGenerateButton.addTarget(self, action: #selector(randomGradient(sender:)), for: .touchUpInside)
    }

    @objc func randomGradient(sender: UIButton)
    {
        let leftGradient = UIColor.random
        let rightGradient = UIColor.random

        gradientView.colorCircleLeftView.backgroundColor = leftGradient
        gradientView.colorCircleRightView.backgroundColor = rightGradient

        //Here is where it's not changing colors. Doesn't seem like the VC recognizes it in this function
        gradientView.mainCircleView.setupGradientBackground(colorOne: leftGradient, colorTwo: rightGradient)
    }

看法：

class GradientView: UIView {
//circle's UIView code in Extensions
    let mainCircleView = UIView().circleView(width: 380, height: 380)
    let colorCircleLeftView = UIView().circleView(width: 40, height: 40)
    let colorCircleRightView = UIView().circleView(width: 40, height: 40)

...

    func setupLayout() {
    ...
    }
}

我嘗試將mainCircleView顏色更改為純 UIColors，例如gradientView.mainCircleView.setupGradientBackground(colorOne: .red, colorTwo: .orange)以查看主 Circle 是否在func newGradient()和 @objc 中都更改為@objc func randomGradient(sender: UIButton) 。 它只會在我手動設置的func newGradient()中發生變化，這意味着 VC 無法識別@objc func中的主 Circle，但我不知道如何修復它......

任何幫助表示贊賞！

單擊“生成”按鈕時的樣子（大圓圈應顯示為棕色和紫色）：

Answer 1

用這個更新你的 function，你必須刪除舊層，然后插入新的子層。

解決方案1：

   func setupGradientBackground(colorOne: UIColor, colorTwo: UIColor) {

        if let gradientLayer = (self.layer.sublayers?.compactMap { $0 as? CAGradientLayer })?.first {
               gradientLayer.removeFromSuperlayer()
        }

        let gradientLayer: CAGradientLayer = CAGradientLayer()
        gradientLayer.colors = [colorOne.cgColor, colorTwo.cgColor]
        gradientLayer.locations = [0.0, 1.0]
        gradientLayer.startPoint = CGPoint(x: 0.0, y: 1.0)
        gradientLayer.endPoint = CGPoint(x: 1.0, y: 0.0)
        gradientLayer.frame = self.bounds
        self.layer.insertSublayer(gradientLayer, at: 0)
    }

解決方案2：

func setupGradientBackground(colorOne: UIColor, colorTwo: UIColor) {

    let gradientLayer = layer.sublayers?.first as? CAGradientLayer ?? CAGradientLayer()

    gradientLayer.colors = [colorOne.cgColor, colorTwo.cgColor]
    gradientLayer.locations = [0.0, 1.0]
    gradientLayer.startPoint = CGPoint(x: 0.0, y: 1.0)
    gradientLayer.endPoint = CGPoint(x: 1.0, y: 0.0)
    gradientLayer.frame = self.bounds

    guard gradientLayer.superlayer != self else {
      return
    }
    layer.insertSublayer(gradientLayer, at: 0)
}

解決方案 3：您可以將名稱設置為CAGradientLayer ，這將幫助您刪除該特定圖層。

   func setupGradientBackground(colorOne: UIColor, colorTwo: UIColor) {
        for layer in layer.sublayers ?? [] {
            if layer.name == "GradientLayer" {
                layer.removeFromSuperlayer()
            }
        }

        let gradientLayer: CAGradientLayer = CAGradientLayer()
        gradientLayer.colors = [colorOne.cgColor, colorTwo.cgColor]
        gradientLayer.locations = [0.0, 1.0]
        gradientLayer.startPoint = CGPoint(x: 0.0, y: 1.0)
        gradientLayer.endPoint = CGPoint(x: 1.0, y: 0.0)
        gradientLayer.name = "GradientLayer"
        gradientLayer.frame = self.bounds

        self.layer.insertSublayer(gradientLayer, at: 0)
    }

Answer 2

漸變不會更改，因為您在現有漸變下方添加了新漸變

extension UIView {

    func setupGradientBackground(colorOne: UIColor, colorTwo: UIColor) {
        let gradientLayer: CAGradientLayer = CAGradientLayer()

        ...

        // ⬇ There is a mistake. 
        self.layer.insertSublayer(gradientLayer, at: 0)
    }
}

你應該用這個新的漸變來改變當前的漸變。 或者在舊的上方插入一個新的。

Answer 3

設置后更改漸變層colors

extension CALayer {   

    func updateGradientColors(_ colors:CGColor...) {
        if let layer = sublayers?.first as? CAGradientLayer {
            let frame = CGRect(origin: self.bounds.origin, size: CGSize(width: self.bounds.size.width, height: self.bounds.size.height))
            layer.frame = frame
            layer.colors = colors
        }
    }

}