使用Swift开发一个贝乐虎启蒙App - 横竖屏切换

前言

接下来我们将做视频播放这块，而视频播放页面是横屏的，所以我们先解决下横竖屏切换问题。

我们先来看下关于方向的两个枚举和一个结构体：

UIDeviceOrientation：设备方向

这个枚举值用来表示物理设备的方向

public enum UIDeviceOrientation : Int {
    case unknown = 0
    case portrait = 1 // Device oriented vertically, home button on the bottom
    case portraitUpsideDown = 2 // Device oriented vertically, home button on the top
    case landscapeLeft = 3 // Device oriented horizontally, home button on the right
    case landscapeRight = 4 // Device oriented horizontally, home button on the left
    case faceUp = 5 // Device oriented flat, face up
    case faceDown = 6 // Device oriented flat, face down
}

这个只能读取，不能去设置，我们可以使用UIDevice.current.orientation来获取设备方向，在代码中监控这个方向的变化

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {

    UIDevice.current.beginGeneratingDeviceOrientationNotifications()
    NotificationCenter.default.addObserver(self, selector: #selector(deviceOrientation), name: UIDevice.orientationDidChangeNotification, object: nil)
    return true
}

@objc private func deviceOrientation() {
    switch UIDevice.current.orientation {
    case .portrait:
        debugPrint("portrait")
    case .portraitUpsideDown:
        debugPrint("portraitUpsideDown")
    case .landscapeLeft:
        debugPrint("landscapeLeft")
    case .landscapeRight:
        debugPrint("landscapeRight")
    case .faceUp:
        debugPrint("faceUp")
    case .faceDown:
        debugPrint("faceDown")
    default:
        debugPrint("unknown")
    }
}

UIInterfaceOrientation：页面方向

这个是可以设置的，注意: UIInterfaceOrientation.landscapeLeft等于UIDeviceOrientation.landscapeRight(反之亦然)，这是因为向左旋转设备需要向右旋转内容

public enum UIInterfaceOrientation : Int {
    case unknown = 0
    case portrait = 1
    case portraitUpsideDown = 2
    case landscapeLeft = 4
    case landscapeRight = 3
}

UIInterfaceOrientationMask：页面方向

这个和UIInterfaceOrientation有什么区别呢？是一种为了支持多种UIInterfaceOrientation而定义的

public struct UIInterfaceOrientationMask : OptionSet {
    public init(rawValue: UInt)
    public static var portrait: UIInterfaceOrientationMask { get }
    public static var landscapeLeft: UIInterfaceOrientationMask { get }
    public static var landscapeRight: UIInterfaceOrientationMask { get }
    public static var portraitUpsideDown: UIInterfaceOrientationMask { get }
    public static var landscape: UIInterfaceOrientationMask { get }
    public static var all: UIInterfaceOrientationMask { get }
    public static var allButUpsideDown: UIInterfaceOrientationMask { get }
}

设置页面横竖屏

1、AppDelegate里面增加一个orientationMask属性

//记录当前界面横竖屏旋转方向
var orientationMask: UIInterfaceOrientationMask = .portrait {
    didSet {
        if orientationMask.contains(.portrait){
            //强制设置成竖屏
            UIDevice.current.setValue(NSNumber(value: UIInterfaceOrientation.portrait.rawValue), forKey: "orientation")
        } else {
            //强制设置成横屏UIDevice.current.setValue(UIInterfaceOrientation.landscapeRight.rawValue, forKey: "orientation")

        }
        /// 刷新，如果不设置的话，当在横屏状态下锁屏，然后在解锁，在返回到上一页会发现屏幕没有更改过来
        UIViewController.attemptRotationToDeviceOrientation()
    }
}

2、在AppDelegate的func application(_ application: UIApplication, supportedInterfaceOrientationsFor window: UIWindow?) -> UIInterfaceOrientationMask方法里面返回orientationMask

func application(_ application: UIApplication, supportedInterfaceOrientationsFor window: UIWindow?) -> UIInterfaceOrientationMask {
    return orientationMask
}

3、在需要的设置屏幕旋转的控制器里面设置旋转方向

3.1、在进入页面的时候设置旋转方向

if let delegate = UIApplication.shared.delegate as? AppDelegate {
    delegate.orientationMask = .landscapeRight
}

3.2、在离开页面的时候更改回来

override func viewWillDisappear(_ animated: Bool) {
    super.viewWillDisappear(animated)

    if let delegate = UIApplication.shared.delegate as? AppDelegate {
        delegate.orientationMask = .portrait
    }
}

现在屏幕旋转搞定了，下一篇就开始做视频播放了