今天，做一個(gè)項(xiàng)目，本意是首頁是要屏幕方向是固定的portrait，rootViewController是navigationController,不論開啟App之前是橫屏或豎屏，進(jìn)到App就變成portrait.

要在UINavigationController的子類里加

    override var shouldAutorotate: Bool{
        return true
    }
    override var supportedInterfaceOrientations: UIInterfaceOrientationMask {
        return .portrait
    }



    override var preferredInterfaceOrientationForPresentation: UIInterfaceOrientation {
        return .portrait
    }

preferredInterfaceOrientationForPresentation: UIInterfaceOrientation這個(gè)方法在啟動(dòng)時(shí)一直沒有調(diào)用，根據(jù)字面的猜想它只在一個(gè)viewController presentation到下一具viewController時(shí)，下一個(gè)viewController會(huì)調(diào)用。

上面這樣設(shè)置會(huì)對(duì)navigationController里所有viewController都有效，如果要對(duì)每個(gè)viewController都有自定義的設(shè)置，請(qǐng)看下面的文章
iOS 橫豎屏切換（控制項(xiàng)目的每一個(gè)ViewController)

最好在func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool里加

        UIApplication.shared.statusBarOrientation = .portrait