1 NavigationController与AutoRotate

1.1 如果一个controller属于UINavigationController，controller的shouldAutorotate方法会失效

1.2 希望UINavigationController中所有controller都不能旋屏

class LNNaviVCNoRotation: UINavigationController {
    override var shouldAutorotate: Bool {
        return false
    }
}

1.3 希望UINavigationController中的controller自己决定能不能旋屏

class LNNaviController: UINavigationController {
    override open var shouldAutorotate: Bool {
        get {
            if let visibleVC = visibleViewController {
                return visibleVC.shouldAutorotate
            }
            return super.shouldAutorotate
        }
    }

    override open var preferredInterfaceOrientationForPresentation: UIInterfaceOrientation{
        get {
            if let visibleVC = visibleViewController {
                return visibleVC.preferredInterfaceOrientationForPresentation
            }
            return super.preferredInterfaceOrientationForPresentation
        }
    }

    override open var supportedInterfaceOrientations: UIInterfaceOrientationMask{
        get {
            if let visibleVC = visibleViewController {
                return visibleVC.supportedInterfaceOrientations
            }
            return super.supportedInterfaceOrientations
        }
    }
}

//特定controller中
override var shouldAutorotate: Bool {
    return true
}

override var preferredInterfaceOrientationForPresentation: UIInterfaceOrientation{
    return .landscapeLeft
}

override var supportedInterfaceOrientations: UIInterfaceOrientationMask {
    return .landscape
}

1.4 如果希望controller在特定情况下不能旋屏，其他时候可以。如present出半屏的视图时，不可旋屏

override var shouldAutorotate: Bool {
    return !lockRotation    //通过设置lockRotation
}

1.5 present 和 shouldAutorotate

如果present的modal不是fullScreen，那么present出来的vc的shouldAutorotate是不起作用的

1.6 强制旋屏

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

    let value = UIInterfaceOrientation.landscapeLeft.rawValue        // 有动效
//        let value = UIDeviceOrientation.landscapeLeft.rawValue    // 无动效
    UIDevice.current.setValue(value, forKey: "orientation")
}

2 生命周期方法 与 Orientation

这个方法中，出方法之前，Device的方向是新的，StatusBar的方向是旧的。

/**
 * 注意: 在iOS15中, override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator)中
 *  UIInterfaceOrientation是滞后的, 也就是旋屏前的方向
 *   UIDevice.current.orientation是旋屏后的最终方向, 并且与设备的实际方向无关, 而是statusBar的方向(如手机横置时, 点bilibli的非全屏播放, 这时手机是横向, 页面内容则是竖着的, UIDevice.current.orientation为 portrait)
 */

//controller
override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
    super.viewWillTransition(to: size, with: coordinator)
    guard !lockRotation else { return }
    //
}

override func viewWillLayoutSubviews() {
    super.viewWillLayoutSubviews()
    let orientation = UIDevice.current.orientation    //注意statusBarOrietation已经废弃了，Device orientation包含了FaceUp等
    if orientation.isLandscape {
      //横屏布局
    } else {
      //竖屏布局
    }
}