UIDeviceOrientation和UIInterfaceO

UIDeviceOrientation

UIDeviceOrientation指的是设备的物理方向，一共有下面七种方向。

public enum UIDeviceOrientation : Int {

    case unknown

    case portrait // Device oriented vertically, home button on the bottom

    case portraitUpsideDown // Device oriented vertically, home button on the top

    case landscapeLeft // Device oriented horizontally, home button on the right

    case landscapeRight // Device oriented horizontally, home button on the left

    case faceUp // Device oriented flat, face up

    case faceDown // Device oriented flat, face down
}

通过UIDevice.current.orientation可以获取当前设备方向，当设备方向变化时，会发出UIDevice.orientationDidChangeNotification通知，监听该通知可以处理设备方向改变事件。

    override func viewDidLoad() {
        super.viewDidLoad()
        //监听通知前判断是否在生成设备方向通知了，没有的话调用beginGeneratingDeviceOrientationNotifications()
        if !UIDevice.current.isGeneratingDeviceOrientationNotifications{
            UIDevice.current.beginGeneratingDeviceOrientationNotifications()
        }
        NotificationCenter.default.addObserver(self, selector: #selector(deviceOrientationDidChange), name: UIDevice.orientationDidChangeNotification, object: nil)
    }

    @objc func deviceOrientationDidChange(sender: AnyObject) {
        print(UIDevice.current.orientation.rawValue)
    }

    deinit {
        NotificationCenter.default.removeObserver(self)
    }

UIInterfaceOrientation

UIInterfaceOrientation指的是界面方向，一共有下面5种方向。

public enum UIInterfaceOrientation : Int {

    
    case unknown

    case portrait

    case portraitUpsideDown

    case landscapeLeft

    case landscapeRight
}

UIInterfaceOrientation和状态栏有关，通过UIApplication.shared.statusBarOrientation可以获取当前界面方向。监听 UIApplication.willChangeStatusBarOrientationNotification和UIApplication.didChangeStatusBarOrientationNotification可以处理界面方向改变事件。

    override func viewDidLoad() {
        super.viewDidLoad()

        NotificationCenter.default.addObserver(self, selector: #selector(interfaceOrientationWillChange), name:
            UIApplication.willChangeStatusBarOrientationNotification,object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(interfaceOrientationDidChange), name:
            UIApplication.didChangeStatusBarOrientationNotification,object: nil)
    }
    
    @objc func interfaceOrientationWillChange(sender: AnyObject) {
        print("interfaceOrientationWillChange:\(UIApplication.shared.statusBarOrientation.rawValue)")
    }
    
    @objc func interfaceOrientationDidChange(sender: AnyObject) {
        print("interfaceOrientationDidChange:\(UIApplication.shared.statusBarOrientation.rawValue)")
    }
    
    deinit {
        NotificationCenter.default.removeObserver(self)
    }

UIKit接收到设备方向改变事件后，通过AppDelegate通知当前程序的UIWindow对象，UIWindow对象通知它的rootViewController，如果该rootViewController支持改变后的界面方向，则改变界面方向。

修改UIApplicationDelegate的supportedInterfaceOrientationsFor方法可以指定App支持的界面方向，该方法的默认值为Info.plist的Supported interface orientations(也可以通过General=>Deployment Info=>Device Orientation修改)。

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

UIViewController可以通过重写supportedInterfaceOrientations修改支持的界面方向，重写preferredInterfaceOrientationForPresentation修改显示的界面方向，这些界面方向不能包含App不支持的界面方向。

    override var supportedInterfaceOrientations: UIInterfaceOrientationMask{
        get{
            return .portrait
        }
    }
    
    override var preferredInterfaceOrientationForPresentation: UIInterfaceOrientation{
        get{
            return .portrait
        }
    }

当UIViewController显示在UINavigationController或UITabBarController中时，支持的界面方向为UINavigationController或UITabBarController支持的界面方向。

    override var supportedInterfaceOrientations: UIInterfaceOrientationMask{
        get{
            return visibleViewController?.supportedInterfaceOrientations ?? .portrait
        }
    }
    
    override var preferredInterfaceOrientationForPresentation: UIInterfaceOrientation{
        get{
            return visibleViewController?.preferredInterfaceOrientationForPresentation ?? .portrait
        }
    }

    override var supportedInterfaceOrientations: UIInterfaceOrientationMask{
        get{
            return selectedViewController?.supportedInterfaceOrientations ?? .portrait
        }
    }
    
    override var preferredInterfaceOrientationForPresentation: UIInterfaceOrientation{
        get{
            return selectedViewController?.preferredInterfaceOrientationForPresentation ?? .portrait
        }
    }

UIDeviceOrientation和UIInterfaceOrientation的区别

UIDeviceOrientation只能读取不能修改，UIInterfaceOrientation可以通过attemptRotationToDeviceOrientation将界面方向修改为与设备方向一致。修改支持的界面方向并不影响设备方向改变通知，例如支持的界面方向为仅竖屏，当手机横屏时依然会收到设备方向改变通知。