iOS 關(guān)于橫豎屏問題

關(guān)于橫豎屏相關(guān)方法的響應(yīng)都是迷之存在，很難琢磨，搞的一頭霧水。最近項目中正好遇到某個控制器需要橫屏展示，查閱WWDC資料未發(fā)現(xiàn)關(guān)于orientation或者rotation相關(guān)資料。
只能通過實驗與猜測大致了解其生命周期了。
首先，當前屏幕是否支持橫豎屏旋轉(zhuǎn)取決于當前window的支持方向。
設(shè)置window橫豎屏的地方有兩處，
第一處，通過工程->General->DeviceOrientation來勾選支持的方向
第二處，通過重寫Appdelegate中的方法來設(shè)置當前window支持的方向

- (UIInterfaceOrientationMask)application:(UIApplication *)application supportedInterfaceOrientationsForWindow:(UIWindow *)window

那么問題來了，既然有兩處都可以設(shè)置，那么最終取值以哪一個為準呢？
通過測試發(fā)現(xiàn)，如果兩處都設(shè)置了，最終以第二種設(shè)置為（主要）判斷依據(jù)；如果第二處未設(shè)置，則以第一處為準。
只有當前window支持某個方向的旋轉(zhuǎn)，才能對控制器（如UIviewcontroller）進行相應(yīng)方向的旋轉(zhuǎn)并達到想要的效果（內(nèi)容跟著轉(zhuǎn)動）。
設(shè)置了可旋轉(zhuǎn)的方向之后，就要對個別控制器做更細致的限制了，比如想讓A控制只能豎屏，或者讓B控制器只能橫屏，就需要用到VC的擴展方法(系統(tǒng)自帶的)

//是否允許旋轉(zhuǎn)
- (BOOL)shouldAutorotate {
    NSLog(@"%s",__FUNCTION__);
    return YES;
}
//present時可支持的旋轉(zhuǎn)方向（present時在supportedInterfaceOrientations前執(zhí)行）
- (UIInterfaceOrientation)preferredInterfaceOrientationForPresentation {
    NSLog(@"%s",__FUNCTION__);
    if (_orientationMask & UIInterfaceOrientationMaskLandscapeLeft) {
        return UIInterfaceOrientationLandscapeLeft;
    }
    return UIInterfaceOrientationPortrait;
}
//支持的旋轉(zhuǎn)方向
- (UIInterfaceOrientationMask)supportedInterfaceOrientations {
    NSLog(@"%s",__FUNCTION__);
    if ([AppDelegate sharedInstance].supportLandscape) {
        return _orientationMask | UIInterfaceOrientationMaskLandscapeLeft;
    } else {
        return UIInterfaceOrientationMaskPortrait;
    }
}

旋轉(zhuǎn)事件的傳遞順序研究

通過創(chuàng)建一個新項目，頁面布局如下：


download.png

分別自定義了UINavigationcontroller和UIviewcontroller，并重寫了vc旋轉(zhuǎn)相關(guān)的三個擴展方法，將UINavigationcontroller設(shè)置為window的rootviewcontroller

//appdelegate中添加的代碼如下
@property(nonatomic, assign, getter=isSupportLandscape) BOOL supportLandscape;
+ (AppDelegate *)sharedInstance;
- (UIInterfaceOrientationMask)application:(UIApplication *)application supportedInterfaceOrientationsForWindow:(UIWindow *)window {
    NSLog(@"%s",__FUNCTION__);
    if (self.isSupportLandscape) {
        return UIInterfaceOrientationMaskAllButUpsideDown;
    } else {
        return UIInterfaceOrientationMaskPortrait;
    }
}

//自定義的nav
- (BOOL)shouldAutorotate {
    NSLog(@"%s",__FUNCTION__);
    return YES;
}

- (UIInterfaceOrientation)preferredInterfaceOrientationForPresentation {
    NSLog(@"%s",__FUNCTION__);
    if ([AppDelegate sharedInstance].supportLandscape) {
        return UIInterfaceOrientationLandscapeLeft;
    }
    return UIInterfaceOrientationPortrait;
}

- (UIInterfaceOrientationMask)supportedInterfaceOrientations {
    NSLog(@"%s",__FUNCTION__);
    return UIInterfaceOrientationMaskAllButUpsideDown;

}

//自定義的vc
- (BOOL)shouldAutorotate {
    NSLog(@"%s",__FUNCTION__);
    return YES;
}

- (UIInterfaceOrientation)preferredInterfaceOrientationForPresentation {
    NSLog(@"%s",__FUNCTION__);
    if ([AppDelegate sharedInstance].supportLandscape) {
        return UIInterfaceOrientationLandscapeLeft;
    }
    return UIInterfaceOrientationPortrait;
}

- (UIInterfaceOrientationMask)supportedInterfaceOrientations {
    NSLog(@"%s",__FUNCTION__);
    return UIInterfaceOrientationMaskAllButUpsideDown;
}

直接啟動APP查看旋轉(zhuǎn)方法調(diào)用情況如下：

2020-08-12 18:54:38.481 rotation[17319:3924945] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-12 18:54:38.481 rotation[17319:3924945] -[NavVC supportedInterfaceOrientations]
2020-08-12 18:54:38.482 rotation[17319:3924945] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-12 18:54:38.482 rotation[17319:3924945] -[NavVC supportedInterfaceOrientations]
2020-08-12 18:54:38.482 rotation[17319:3924945] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-12 18:54:38.483 rotation[17319:3924945] -[NavVC supportedInterfaceOrientations]
2020-08-12 18:54:38.483 rotation[17319:3924945] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-12 18:54:38.483 rotation[17319:3924945] -[NavVC supportedInterfaceOrientations]
2020-08-12 18:54:38.496 rotation[17319:3924945] -[NavVC viewWillAppear:]
2020-08-12 18:54:38.498 rotation[17319:3924945] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-12 18:54:38.498 rotation[17319:3924945] -[NavVC supportedInterfaceOrientations]
2020-08-12 18:54:38.499 rotation[17319:3924945] -[NavVC shouldAutorotate]
2020-08-12 18:54:38.546 rotation[17319:3924945] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-12 18:54:38.546 rotation[17319:3924945] -[NavVC supportedInterfaceOrientations]
2020-08-12 18:54:38.547 rotation[17319:3924945] -[NavVC shouldAutorotate]
2020-08-12 18:54:38.547 rotation[17319:3924945] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-12 18:54:38.547 rotation[17319:3924945] -[NavVC supportedInterfaceOrientations]
2020-08-12 18:54:38.583 rotation[17319:3924945] -[ViewController viewWillAppear:]
2020-08-12 18:54:38.585 rotation[17319:3924945] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-12 18:54:38.585 rotation[17319:3924945] -[ViewController supportedInterfaceOrientations]

通過以上打印結(jié)果可以看出，APP啟動時，調(diào)用順序為APPdelegate的application:supportedInterfaceOrientationsForWindow: -> nav的supportedInterfaceOrientations -> nav的shouldAutorotate -> vc的supportedInterfaceOrientations

通過以上結(jié)果論證得出結(jié)論：APP在監(jiān)聽到旋轉(zhuǎn)時，會首先通知window 并執(zhí)行delegate中的supportedInterfaceOrientationsForWindow方法，然后通知rootviewcontroller并執(zhí)行supportedInterfaceOrientations方法,最后通知棧頂vc并執(zhí)行supportedInterfaceOrientations。
以上例子我們發(fā)現(xiàn)只調(diào)用了nav的shouldAutorotate，而棧頂vc的shouldAutorotate方法被忽略了，或許我們可以猜測出，是否能夠旋轉(zhuǎn)取決于vc的父容器即nav。
此時，我們手動旋轉(zhuǎn)模擬器，看看打印結(jié)果如何?

2020-08-12 19:32:08.191 rotation[18013:3934444] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-12 19:32:08.191 rotation[18013:3934444] -[NavVC supportedInterfaceOrientations]
2020-08-12 19:32:08.191 rotation[18013:3934444] -[NavVC shouldAutorotate]
2020-08-12 19:32:08.191 rotation[18013:3934444] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-12 19:32:08.191 rotation[18013:3934444] -[NavVC supportedInterfaceOrientations]
2020-08-12 19:32:08.199 rotation[18013:3934444] -[NavVC shouldAutorotate]
2020-08-12 19:32:08.199 rotation[18013:3934444] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-12 19:32:08.200 rotation[18013:3934444] -[NavVC supportedInterfaceOrientations]
2020-08-12 19:32:08.202 rotation[18013:3934444] -[NavVC shouldAutorotate]
2020-08-12 19:32:08.202 rotation[18013:3934444] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-12 19:32:08.202 rotation[18013:3934444] -[NavVC supportedInterfaceOrientations]

通過以上打印結(jié)果可以看出，手動旋轉(zhuǎn)APP時，調(diào)用順序為APPdelegate的application:supportedInterfaceOrientationsForWindow: -> nav的supportedInterfaceOrientations -> nav的shouldAutorotate
即使，手動旋轉(zhuǎn)手機，也沒有調(diào)用vc的shouldAutorotate方法，甚至連vc的supportedInterfaceOrientations方法都沒有調(diào)用，

據(jù)此可以猜測當被旋轉(zhuǎn)的視圖容器為uinavigationcontroller時，其vc內(nèi)容是否能夠旋轉(zhuǎn)取決于nav的支持方向；即使我們設(shè)置vc的方向僅為橫向，最終方向還是取決于nav的支持方向。

為了進一步驗證猜想，我們點擊push按鈕，跳轉(zhuǎn)到另一個只允許橫屏的自定義vc（LandscapeRightVC），打印結(jié)果如下:

2020-08-12 20:08:45.697 rotation[20626:3970125] -[ViewController viewWillDisappear:]
2020-08-12 20:08:45.698 rotation[20626:3970125] -[LandscapeRightVC viewWillAppear:]
2020-08-12 20:08:45.698 rotation[20626:3970125] -[LandscapeRightVC switchToLandscapeRight]
2020-08-12 20:08:45.698 rotation[20626:3970125] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-12 20:08:45.698 rotation[20626:3970125] -[NavVC supportedInterfaceOrientations]
2020-08-12 20:08:45.698 rotation[20626:3970125] -[NavVC shouldAutorotate]
2020-08-12 20:08:45.699 rotation[20626:3970125] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-12 20:08:45.699 rotation[20626:3970125] -[NavVC supportedInterfaceOrientations]
2020-08-12 20:08:45.705 rotation[20626:3970125] -[NavVC shouldAutorotate]
2020-08-12 20:08:45.706 rotation[20626:3970125] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-12 20:08:45.706 rotation[20626:3970125] -[NavVC supportedInterfaceOrientations]
2020-08-12 20:08:45.714 rotation[20626:3970125] -[NavVC shouldAutorotate]
2020-08-12 20:08:45.715 rotation[20626:3970125] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-12 20:08:45.726 rotation[20626:3970125] -[NavVC supportedInterfaceOrientations]

通過打印可以看到只調(diào)用了LandscapeRightVC的旋轉(zhuǎn)方向的方法，而supportedInterfaceOrientations、shouldAutorotate方法均未調(diào)用，但屏幕方向確實已經(jīng)橫屏了，之所以能夠橫屏?xí)r因為此時nav支持橫屏方向，進一步驗證了以上觀點。

我們再將當前nav設(shè)置為只支持豎屏，并且點擊present按鈕，跳轉(zhuǎn)到只支持橫屏的vc看看打印情況：

2020-08-12 20:15:28.471 rotation[20923:3973796] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-12 20:15:28.471 rotation[20923:3973796] -[NavVC supportedInterfaceOrientations]
2020-08-12 20:15:28.472 rotation[20923:3973796] -[LandscapeRightVC preferredInterfaceOrientationForPresentation]
2020-08-12 20:15:28.472 rotation[20923:3973796] -[LandscapeRightVC supportedInterfaceOrientations]
2020-08-12 20:15:28.477 rotation[20923:3973796] -[NavVC shouldAutorotate]
2020-08-12 20:15:28.477 rotation[20923:3973796] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-12 20:15:28.477 rotation[20923:3973796] -[NavVC supportedInterfaceOrientations]
2020-08-12 20:15:28.477 rotation[20923:3973796] -[LandscapeRightVC shouldAutorotate]
2020-08-12 20:15:28.477 rotation[20923:3973796] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-12 20:15:28.478 rotation[20923:3973796] -[LandscapeRightVC supportedInterfaceOrientations]
2020-08-12 20:15:28.481 rotation[20923:3973796] -[ViewController viewWillDisappear:]
2020-08-12 20:15:28.482 rotation[20923:3973796] -[NavVC viewWillDisappear:]
2020-08-12 20:15:28.482 rotation[20923:3973796] -[LandscapeRightVC viewWillAppear:]
2020-08-12 20:15:28.500 rotation[20923:3973796] -[LandscapeRightVC switchToLandscapeRight]
2020-08-12 20:15:29.005 rotation[20923:3973796] -[NavVC shouldAutorotate]
2020-08-12 20:15:29.006 rotation[20923:3973796] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-12 20:15:29.006 rotation[20923:3973796] -[NavVC supportedInterfaceOrientations]
2020-08-12 20:15:29.007 rotation[20923:3973796] -[LandscapeRightVC shouldAutorotate]
2020-08-12 20:15:29.008 rotation[20923:3973796] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-12 20:15:29.008 rotation[20923:3973796] -[LandscapeRightVC supportedInterfaceOrientations]

執(zhí)行順序大致是：
[AppDelegate application:supportedInterfaceOrientationsForWindow:] ->
[NavVC supportedInterfaceOrientations] ->
[LandscapeRightVC preferredInterfaceOrientationForPresentation] ->
[LandscapeRightVC supportedInterfaceOrientations] ->
[NavVC shouldAutorotate] ->
[LandscapeRightVC shouldAutorotate] ->
[LandscapeRightVC supportedInterfaceOrientations]


image.png

通過present后確實已經(jīng)橫屏，得出結(jié)論，如果是從vc中present出來的視圖，即使上一層nav不支持橫屏，最終屏幕旋轉(zhuǎn)方向取決于被present出來的視圖容器所支持的屏幕方向。

總結(jié)：

屏幕旋轉(zhuǎn)的需求大概有兩種：

1.通過翻轉(zhuǎn)手機自動旋轉(zhuǎn)內(nèi)容

2.項目只支持豎屏或橫屏模式，個別頁面需要強制橫屏或豎屏展示

以上兩種需求其實都可以通過 設(shè)置appdelegate -> nav或tabbar 來支持需要旋轉(zhuǎn)的方向，唯一區(qū)別在于需求1中無需強制執(zhí)行代碼來旋轉(zhuǎn)方向，屬于被動旋轉(zhuǎn)；而需求2則要在需要旋轉(zhuǎn)到固定方向的vc中做強制旋轉(zhuǎn)。

//通過代碼強制旋轉(zhuǎn)
//為了防止plus及ipad機型自帶桌面旋轉(zhuǎn)功能時，橫屏失敗，所以先強制旋轉(zhuǎn)到其他方向，再設(shè)置橫屏才會有效果
[[UIDevice currentDevice] setValue:@(UIDeviceOrientationFaceDown) forKey:@"orientation"];  
[[UIDevice currentDevice] setValue:@(UIDeviceOrientationLandscapeRight) forKey:@"orientation"];

那么對于一個項目中個別頁面需要橫屏?xí)r，我們大致可以進行如下寫法：

//AppDelegate中
@property(nonatomic, assign, getter=isSupportLandscape) BOOL supportLandscape;
+ (AppDelegate *)sharedInstance {
    return (AppDelegate *)[UIApplication sharedApplication].delegate;
}
- (UIInterfaceOrientationMask)application:(UIApplication *)application supportedInterfaceOrientationsForWindow:(UIWindow *)window {
    NSLog(@"%s",__FUNCTION__);
    if (self.isSupportLandscape) {
        return UIInterfaceOrientationMaskAllButUpsideDown;
    } else {
        return UIInterfaceOrientationMaskPortrait;
    }
}

//自定義的Navigationcontroller中
//雖然nav是控制旋轉(zhuǎn)的主要因素，但為了保持和最上層vc的旋轉(zhuǎn)方向一致，這里統(tǒng)一取topvc的方向設(shè)置
- (BOOL)shouldAutorotate {
    NSLog(@"%s",__FUNCTION__);
    return [self.viewControllers.lastObject shouldAutorotate];
}

- (UIInterfaceOrientationMask)supportedInterfaceOrientations {
    NSLog(@"%s",__FUNCTION__);
    return [self.viewControllers.lastObject supportedInterfaceOrientations];
}

- (UIInterfaceOrientation)preferredInterfaceOrientationForPresentation {
    NSLog(@"%s",__FUNCTION__);
    return [self.viewControllers.lastObject preferredInterfaceOrientationForPresentation];

//需要橫屏展示的vc中
@interface LandscapeRightVC ()
@property (nonatomic, assign) UIInterfaceOrientationMask orientationMask;
@end

@implementation LandscapeRightVC
- (instancetype)init {
    self = [super init];
    if (self) {
        _orientationMask = UIInterfaceOrientationMaskLandscapeLeft|UIInterfaceOrientationMaskPortrait;
    }
    return self;
}
- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.
    self.title = NSStringFromClass([self class]);
    self.view.backgroundColor = [UIColor whiteColor];
}

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
     [AppDelegate sharedInstance].supportLandscape = YES;
    NSLog(@"%s",__FUNCTION__);
    [self switchToLandscapeRight];
}

- (void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];
    [AppDelegate sharedInstance].supportLandscape = NO;
    NSLog(@"%s",__FUNCTION__);
    [self switchToLandscapePortrait];
}

- (BOOL)shouldAutorotate {
    NSLog(@"%s",__FUNCTION__);
    return YES;
}

- (UIInterfaceOrientation)preferredInterfaceOrientationForPresentation {
    NSLog(@"%s",__FUNCTION__);
//這里加入[AppDelegate sharedInstance].supportLandscape判斷，是為了防止appdelegate中不支持目標方向，而產(chǎn)生Supported orientations has no common orientation with the application的錯誤
    if ([AppDelegate sharedInstance].supportLandscape) {
        if (_orientationMask & UIInterfaceOrientationMaskLandscapeLeft) {
            return UIInterfaceOrientationLandscapeLeft;
        }
    }
    return UIInterfaceOrientationPortrait;
}

- (UIInterfaceOrientationMask)supportedInterfaceOrientations {
    NSLog(@"%s",__FUNCTION__);
//這里加入[AppDelegate sharedInstance].supportLandscape判斷，是為了防止appdelegate中不支持目標方向，而產(chǎn)生Supported orientations has no common orientation with the application的錯誤
    if ([AppDelegate sharedInstance].supportLandscape) {
        return _orientationMask | UIInterfaceOrientationMaskLandscapeLeft;
    } else {
        return UIInterfaceOrientationMaskPortrait;
    }
}

// 手動設(shè)置橫屏
- (void)switchToLandscapeRight {
    NSLog(@"%s",__FUNCTION__);
    _orientationMask = UIInterfaceOrientationMaskLandscapeLeft;
    //為了防止plus及ipad機型自帶桌面旋轉(zhuǎn)功能時，橫屏失敗，所以先強制旋轉(zhuǎn)到其他方向，再設(shè)置橫屏才會有效果
    [[UIDevice currentDevice] setValue:@(UIDeviceOrientationFaceDown) forKey:@"orientation"];
    [[UIDevice currentDevice] setValue:@(UIDeviceOrientationLandscapeRight) forKey:@"orientation"];
}

// 手動設(shè)置豎屏
- (void)switchToLandscapePortrait {
    NSLog(@"%s",__FUNCTION__);
    _orientationMask = UIInterfaceOrientationMaskPortrait;
    [[UIDevice currentDevice] setValue:@(UIDeviceOrientationFaceDown) forKey:@"orientation"];
    [[UIDevice currentDevice] setValue:@(UIDeviceOrientationPortrait) forKey:@"orientation"];
}

延伸：測試一下UITabbarController是如何響應(yīng)的

假如將rootviewcontroller設(shè)置為tabbar，并將tabbar設(shè)置為只支持豎屏，而將其中一個item設(shè)置為LandscapeRightVC，打印結(jié)果如下：

2020-08-13 18:19:59.440 rotation[84659:4616469] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-13 18:19:59.440 rotation[84659:4616469] -[CusTabViewController supportedInterfaceOrientations]
2020-08-13 18:19:59.443 rotation[84659:4616469] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-13 18:19:59.443 rotation[84659:4616469] -[CusTabViewController supportedInterfaceOrientations]
2020-08-13 18:19:59.443 rotation[84659:4616469] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-13 18:19:59.444 rotation[84659:4616469] -[CusTabViewController supportedInterfaceOrientations]
2020-08-13 18:19:59.444 rotation[84659:4616469] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-13 18:19:59.444 rotation[84659:4616469] -[CusTabViewController supportedInterfaceOrientations]
2020-08-13 18:19:59.453 rotation[84659:4616469] -[LandscapeRightVC viewWillAppear:]
2020-08-13 18:19:59.453 rotation[84659:4616469] -[LandscapeRightVC switchToLandscapeRight]
2020-08-13 18:19:59.453 rotation[84659:4616469] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-13 18:19:59.454 rotation[84659:4616469] -[CusTabViewController supportedInterfaceOrientations]
2020-08-13 18:19:59.454 rotation[84659:4616469] -[CusTabViewController shouldAutorotate]
2020-08-13 18:19:59.454 rotation[84659:4616469] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-13 18:19:59.454 rotation[84659:4616469] -[CusTabViewController supportedInterfaceOrientations]
2020-08-13 18:19:59.455 rotation[84659:4616469] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-13 18:19:59.455 rotation[84659:4616469] -[LandscapeRightVC supportedInterfaceOrientations]
2020-08-13 18:19:59.456 rotation[84659:4616469] -[CusTabViewController shouldAutorotate]
2020-08-13 18:19:59.456 rotation[84659:4616469] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-13 18:19:59.457 rotation[84659:4616469] -[CusTabViewController supportedInterfaceOrientations]
2020-08-13 18:19:59.457 rotation[84659:4616469] -[CusTabViewController shouldAutorotate]
2020-08-13 18:19:59.457 rotation[84659:4616469] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-13 18:19:59.457 rotation[84659:4616469] -[CusTabViewController supportedInterfaceOrientations]
2020-08-13 18:19:59.458 rotation[84659:4616469] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-13 18:19:59.458 rotation[84659:4616469] -[CusTabViewController supportedInterfaceOrientations]
2020-08-13 18:19:59.458 rotation[84659:4616469] -[AppDelegate application:supportedInterfaceOrientationsForWindow:]
2020-08-13 18:19:59.458 rotation[84659:4616469] -[CusTabViewController supportedInterfaceOrientations]

可以看到tabbar的傳遞順序與nav類似，并且屬于是視圖容器，假如tabbar不支持橫屏，那么子控制器無論如何旋轉(zhuǎn)都不會有效

順便提一提UIDeviceOrientation（設(shè)備方向）和UIInterfaceOrientation（UI方向）的區(qū)別


typedef NS_ENUM(NSInteger, UIInterfaceOrientation) {
    UIInterfaceOrientationUnknown            = UIDeviceOrientationUnknown,
    UIInterfaceOrientationPortrait           = UIDeviceOrientationPortrait,
    UIInterfaceOrientationPortraitUpsideDown = UIDeviceOrientationPortraitUpsideDown,
    UIInterfaceOrientationLandscapeLeft      = UIDeviceOrientationLandscapeRight,
    UIInterfaceOrientationLandscapeRight     = UIDeviceOrientationLandscapeLeft
} API_UNAVAILABLE(tvos);

typedef NS_ENUM(NSInteger, UIDeviceOrientation) {
    UIDeviceOrientationUnknown,
    UIDeviceOrientationPortrait,            // Device oriented vertically, home button on the bottom
    UIDeviceOrientationPortraitUpsideDown,  // Device oriented vertically, home button on the top
    UIDeviceOrientationLandscapeLeft,       // Device oriented horizontally, home button on the right
    UIDeviceOrientationLandscapeRight,      // Device oriented horizontally, home button on the left
    UIDeviceOrientationFaceUp,              // Device oriented flat, face up
    UIDeviceOrientationFaceDown             // Device oriented flat, face down
} API_UNAVAILABLE(tvos);

可以看到橫向的方向命名是相反的，在使用時需要注意

思考：如果rootviewcontroller是nav，而nav的root是tabbar，tabbar的item又是nav 那么子視圖的旋轉(zhuǎn)又是如何受約束的呢？我猜應(yīng)該是， 取當前棧頂容器（如果是push，則取當前棧頂容器nav，如果是present，則取當前present棧頂中的容器nav或vc，且present的視圖不受parent視圖的橫豎屏限制）

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