Ios iPhone旋转时CALayer的自动旋转

我有一个UIViewController，我在其中向视图的层添加一个CALayer子类：

[self.view.layer addSublayer:myObject.backgroundLayer];

旋转设备时，视图会旋转，但CALayer不会旋转。它被分流到左边，仍然在纵向视图中

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有没有办法使子层自动旋转，或者我需要应用变换？

您需要自己管理CALayer的旋转。我相信0,0保持在同一位置，并且大小会更改以匹配新方向，因此如果您想自己做一些事情，您需要自己管理旋转变换的添加。

使用Swift 4/iOS 11，根据您的需要，您可以选择以下6个示例中的一个，以便在设备旋转时管理

CALayer

/

CAGradientLayer

帧

下面的示例使用

CAGradientLayer

，但可以轻松映射到

CALayer

或

CAShapeLayer

案例

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#1.重写

UIViewController

viewDidLayoutSubviews（）

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#2.重写

UIViewController

loadView（）

，子类化

UIView

并重写

UIView

LayoutSubView（）

斯威夫特

LayerView.swift（备选方案）

ViewController.swift

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#3.使用键值观察（KVO） ViewController.swift

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#5.重写

UIViewController

loadView（）

，子类化

UIView

并重写

CALayerDelegate

布局子层（共：）

斯威夫特

ViewController.swift

---

#6.覆盖

UIViewController

loadView（）

，子类化

UIView

，覆盖

UIView

layerClass

，子类化

CALayer

和覆盖

CALayer

layoutSublayers（） 斯威夫特

斯威夫特

ViewController.swift

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资料来源：

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您的代码中有一些错误……如果您重写一个函数，您首先要做什么…叫超级

import UIKit

class ViewController: UIViewController {

    let gradientLayer: CAGradientLayer = {
        let layer = CAGradientLayer()
        layer.colors = [
            UIColor.blue.cgColor,
            UIColor.cyan.cgColor
        ]
        return layer
    }()

    override func viewDidLoad() {
        super.viewDidLoad()

        view.layer.addSublayer(gradientLayer)
        gradientLayer.frame = view.bounds
    }

    override func viewDidLayoutSubviews() {         
        gradientLayer.frame = view.bounds
    }

}

import UIKit

class LayerView: UIView {

    lazy var gradientLayer: CAGradientLayer = {
        let layer = CAGradientLayer()
        layer.colors = [
            UIColor.blue.cgColor,
            UIColor.cyan.cgColor
        ]
        self.layer.addSublayer(layer)
        return layer
    }()

    override func layoutSubviews() {
        gradientLayer.frame = bounds
    }

}

import UIKit

class LayerView: UIView {

    var gradientLayer: CAGradientLayer!

    override func layoutSubviews() {
        if gradientLayer == nil {
            let gradientLayer = CAGradientLayer()
            gradientLayer.colors = [
                UIColor.blue.cgColor,
                UIColor.cyan.cgColor
            ]
            self.gradientLayer = gradientLayer
            layer.addSublayer(gradientLayer)
        }

        gradientLayer.frame = bounds
    }

}

import UIKit

class ViewController: UIViewController {

    let layerView = LayerView()

    override func loadView() {
        view = layerView
    }

}

import UIKit

class ViewController: UIViewController {

    var observation: NSKeyValueObservation?

    let gradientLayer: CAGradientLayer = {
        let layer = CAGradientLayer()
        layer.colors = [
            UIColor.blue.cgColor,
            UIColor.cyan.cgColor
        ]
        return layer
    }()

    override func viewDidLoad() {
        super.viewDidLoad()

        view.layer.addSublayer(gradientLayer)

        observation = view.observe(\.frame, options: [.new], changeHandler: { [unowned self] (object: UIView, change: NSKeyValueObservedChange<CGRect>) in
            guard let frame = change.newValue else { return }
            self.gradientLayer.frame = frame
        })

        // Also works
        /*
        observation = observe(\.view.frame, options: [.new], changeHandler: { [unowned self] (object: ViewController, change: NSKeyValueObservedChange<CGRect>) in
            guard let frame = change.newValue else { return }
            self.gradientLayer.frame = frame
        })
        */
    }

}

import UIKit

class LayerView: UIView {

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

    required init() {
        super.init(frame: .zero)

        guard let gradientLayer = layer as? CAGradientLayer else { return }
        gradientLayer.colors = [
            UIColor.blue.cgColor,
            UIColor.cyan.cgColor
        ]
    }

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

}

import UIKit

class ViewController: UIViewController {

    let layerView = LayerView()

    override func loadView() {
        view = layerView
    }

}

import UIKit

class LayerView: UIView {

    required init() {
        super.init(frame: .zero)

        let gradientLayer = CAGradientLayer()
        gradientLayer.colors = [
            UIColor.blue.cgColor,
            UIColor.cyan.cgColor
        ]

        layer.addSublayer(gradientLayer)
    }

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

    override func layoutSublayers(of layer: CALayer) {
        layer.sublayers?.forEach {
            $0.frame = layer.bounds
        }
    }

}

import UIKit

class ViewController: UIViewController {

    let layerView = LayerView()

    override func loadView() {
        view = layerView
    }

}

import UIKit

class Layer: CALayer {

    override init() {
        super.init()

        let gradientLayer = CAGradientLayer()
        gradientLayer.colors = [
            UIColor.blue.cgColor,
            UIColor.cyan.cgColor
        ]

        addSublayer(gradientLayer)
    }

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

    override func layoutSublayers() {
        sublayers?.forEach {
            $0.frame = bounds
        }
    }

}

import UIKit

class LayerView: UIView {

    override public class var layerClass: AnyClass {
        return Layer.self
    }

}

import UIKit

class ViewController: UIViewController {

    let layerView = LayerView()

    override func loadView() {
        view = layerView
    }

}