从旋转的子视图中删除渐变

Question

我可以从子视图中删除渐变，但是，如果将按钮添加到子视图中，则无法删除渐变层。如何在旋转时从子视图中移除渐变。

这里是视图控制器的代码。

import UIKit

class ViewController: UIViewController {

@IBOutlet weak var buttonOutlet: UIButton!

@IBOutlet weak var labelOutlet: UILabel!


@IBOutlet weak var mySubView: UIView!

@IBOutlet weak var mySubView2: UIView!

@IBOutlet weak var mySubView3: UIView!


override func viewDidLayoutSubviews() {
     addGradient()
 }


fileprivate func addGradient() {
    mySubView.mainGradientBackground()
    mySubView2.subGradientBackground()
    mySubView3.subGradientBackground()
    labelOutlet.labelTextfieldShadow()
    buttonOutlet.buttonGradientBackground(cornerRadius: 10, shadowRadius: 3)
}



 /// This will let you know when the device rotates.
   override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
       if UIDevice.current.orientation.isValidInterfaceOrientation {

        removeSublayer(mySubView, layerIndex: 0)
        removeSublayer(mySubView, layerIndex: 0)

        removeSublayer(mySubView2, layerIndex: 0)
        removeSublayer(mySubView2, layerIndex: 0)

        removeSublayer(mySubView3, layerIndex: 0)
        removeSublayer(mySubView3, layerIndex: 0)

        removeSublayer(buttonOutlet, layerIndex: 0)
        removeSublayer(buttonOutlet, layerIndex: 0)

        removeSublayer(labelOutlet, layerIndex: 0)

       }
   }


func removeSublayer(_ view: UIView, layerIndex index: Int) {
    guard let sublayers = view.layer.sublayers else {
        print("The view does not have any sublayers.")
        return
    }
    if sublayers.count > index {
        view.layer.sublayers!.remove(at: index)
    } else {
        print("There are not enough sublayers to remove that index.")
    }
}


}

这是用于为我需要的任何视图着色的渐变扩展。

import Foundation
import UIKit

extension UIView {


/// Use this to set a gradient for the background.
/// = This is a gradient with no shadow.
func mainGradientBackground() {
    let color = Color()

    let leading = color.backgroundLeading
    let trailing = color.backgroundTrailing

    let gradientLayer = CAGradientLayer()
    gradientLayer.frame = bounds
    gradientLayer.colors = [leading, trailing]
    gradientLayer.locations = [0,0.3]
    gradientLayer.startPoint = CGPoint(x: 0.05, y: 0.5)
    gradientLayer.endPoint = CGPoint(x: 0.75, y: 0.5)

     layer.insertSublayer(gradientLayer, at: 0)
}



/// Use this to set a gradient for the background.
/// = This is a gradient with a shadow.
 func subGradientBackground() {

    let corner: CGFloat = 15

    let color = Color()

    let leading = color.subBackgroundLeading
    let trailing = color.subBackgroundTrailing
    let borderColor = color.subBorderColor

    let gradientLayer = CAGradientLayer()
    gradientLayer.frame = bounds
    gradientLayer.colors = [leading, trailing]
    gradientLayer.locations = [0,0.3,1]
    gradientLayer.startPoint = CGPoint(x: 0.05, y: 0.5)
    gradientLayer.endPoint = CGPoint(x: 0.75, y: 0.5)
    gradientLayer.borderColor = borderColor
    gradientLayer.borderWidth = 4
    gradientLayer.cornerRadius = corner
    layer.insertSublayer(gradientLayer, at: 0)

    let subLayer = CALayer()
    subLayer.frame = bounds
    subLayer.shadowPath = UIBezierPath(roundedRect: bounds, cornerRadius: corner - 2).cgPath
    subLayer.shadowColor = UIColor.red.cgColor
    subLayer.shadowOpacity = 1
    subLayer.shadowRadius = 2

    subLayer.shadowOffset = CGSize(width: 3, height: 4)

    layer.insertSublayer(subLayer, at: 0)

}

  /// Use this to set a gradient for the background.
  /// = This is a gradient with a shadow.
   func subGradientBackgroundShadow() {

      let corner: CGFloat = 15

      let subLayer = CALayer()
      subLayer.frame = bounds
      subLayer.shadowPath = UIBezierPath(roundedRect: bounds, cornerRadius: corner - 2).cgPath
      subLayer.shadowColor = UIColor.red.cgColor
      subLayer.shadowOpacity = 1
      subLayer.shadowRadius = 2

      subLayer.shadowOffset = CGSize(width: 3, height: 4)

      layer.insertSublayer(subLayer, at: 0)
  }



/// LabelShadow
/// - Parameter masksToBounds: Keep the layer in its bound
/// - Exp.. Set to true to keep text in textview in its frame.
/// - Exp.. Set to false to let shadow out side the frame.
/// - Defalr corner radius is 7
func labelTextfieldShadow() {
    let color = Color()

    let dark = color.labelBackgroundDark
    let borderColor = color.labelBorderColor

    layer.masksToBounds = false
    layer.borderWidth = 0.5
    layer.borderColor = borderColor
    layer.cornerRadius = 7
    self.backgroundColor = dark

    layer.shadowRadius = 7
    layer.shadowColor = UIColor.black.cgColor
    layer.shadowOffset = CGSize(width: 3, height: 3)
    layer.shadowOpacity = 0.6
}



/// Button gradient
/// - Parameter cornerRadius: Set the radius of the button. Use outlet height / 2
/// - Parameter shadowRadius: Set the shadow radius. 2
func buttonGradientBackground(cornerRadius: CGFloat, shadowRadius: CGFloat) {
    let color = Color()

    let leading = color.buttonLeading
    let middle = color.buttonMiddle
    let trailing = color.buttonTrailing
    let borderColor = color.buttonBorderColor

    let gradientLayer = CAGradientLayer()
    gradientLayer.frame = bounds
    gradientLayer.colors = [leading, middle, trailing]
    gradientLayer.locations = [0,0.3,1]
    gradientLayer.startPoint = CGPoint(x: 0.05, y: 0.5)
    gradientLayer.endPoint = CGPoint(x: 0.75, y: 0.5)
    gradientLayer.borderColor = borderColor
    gradientLayer.borderWidth = 1
    gradientLayer.cornerRadius = cornerRadius
    layer.insertSublayer(gradientLayer, at: 0)

    let subLayer = CALayer()
    subLayer.frame = bounds
    subLayer.shadowPath = UIBezierPath(roundedRect: bounds, cornerRadius: cornerRadius - 2).cgPath
    subLayer.shadowColor =  UIColor.black.cgColor
    subLayer.shadowOpacity = 1
    subLayer.shadowRadius = shadowRadius
    subLayer.shadowOffset = CGSize(width: 2, height: 3)
    layer.insertSublayer(subLayer, at: 0)
}

}

这里是屏幕的四个屏幕截图。

] 2] 3] 4

这是一种颜色结构，用于为所有视图着色。主视图，子视图，标签和按钮。

结构颜色{

// Use these colors to style the main background.
/// This color is used for the main view's background leading greadient color.
let backgroundLeading = #colorLiteral(red: 0.2745098039, green: 0.231372549, blue: 0.231372549, alpha: 1).cgColor

/// TThis color is used for the main view's background trailing greadient color.
let backgroundTrailing = #colorLiteral(red: 0.2784313725, green: 0.2352941176, blue: 0.2352941176, alpha: 1).cgColor



// Use these colors to style the sub view.
/// This color is used for the sub view's leading greadient color.
let subBackgroundLeading = #colorLiteral(red: 0.1960784314, green: 0.2549019608, blue: 0.2549019608, alpha: 1).cgColor

/// This color is used for the sub view's trailing greadient color.
let subBackgroundTrailing = #colorLiteral(red: 0.1012082246, green: 0.2111029723, blue: 0.1947238818, alpha: 1).cgColor

/// This color is used for the sub view's border.
let subBorderColor = #colorLiteral(red: 0.6000000238, green: 0.6000000238, blue: 0.6000000238, alpha: 1).cgColor



// Use these colors to style the labels.
/// This color is used for editing text background.
let labelBackgroundLight = #colorLiteral(red: 0.921431005, green: 0.9214526415, blue: 0.9214410186, alpha: 1) as UIColor

/// This color is used for disabled text background.
let labelBackgroundDark = #colorLiteral(red: 0.1843137255, green: 0.137254902, blue: 0.1384684741, alpha: 1) as UIColor

/// This color is used for the label's border.
let labelBorderColor = #colorLiteral(red: 0.6, green: 0.6, blue: 0.6, alpha: 1).cgColor



// Use these colors to style the buttons.
/// This color is used for the button's leading greadient color.
let buttonLeading = #colorLiteral(red: 0.1960784314, green: 0.2549019608, blue: 0.2549019608, alpha: 1).cgColor

/// This color is used for the button's middle greadient color.
let buttonMiddle = #colorLiteral(red: 0.2, green: 0.2, blue: 0.2, alpha: 1).cgColor

/// This color is used for the button's trailing greadient color.
let buttonTrailing = #colorLiteral(red: 0.1012082246, green: 0.2111029723, blue: 0.1947238818, alpha: 1).cgColor

/// This color is used for the button's border color.
let buttonBorderColor = #colorLiteral(red: 0.6000000238, green: 0.6000000238, blue: 0.6000000238, alpha: 1).cgColor


// Use these colors for the text
/// This color is used for the deiabled label and text field.
let labelDisableColor = #colorLiteral(red: 0.8039215803, green: 0.8039215803, blue: 0.8039215803, alpha: 1)

/// This color is used for the enabled label and text field.
let labelEnableColor = #colorLiteral(red: 1.0, green: 1.0, blue: 1.0, alpha: 1.0)

/// The text color white.
let labelWhiteTextColor = #colorLiteral(red: 1, green: 1, blue: 1, alpha: 1)

/// The text color Black
let labelBlackTextColor = #colorLiteral(red: 0, green: 0, blue: 0, alpha: 1)
}

Answer 1

而不是假设某个层位于给定索引处，只需将要删除的后一个保留为实例变量（或放置在CALayers数组中，然后将其从上一层告知remove themselves 。

例如：

var layersToRemoveLater = [CALayer]()
...
layersToRemoveLater.append(someLayer)
layersToRemoveLater.append(someOtherLayer)
...
layersToRemoveLater.forEach { $0.removeFromSuperLayer() }