iOS屏幕旋转与锁屏

在做视频开发时遇到屏幕旋转问题,其中涉及到 StatusBar、 UINavigationController、UITabBarController 、UIViewcontroller。

在设备锁屏下的整体效果图

主要涉及以下4点：
- 横竖屏的旋转
- 屏幕旋转相应改变视图位置
- 旋转时状态栏的隐藏与显示
- 锁屏

1、横竖屏旋转

• 第1步：

   -(UIInterfaceOrientationMask)application:(UIApplication *)application supportedInterfaceOrientationsForWindow:(UIWindow *)window {
  
  //    NSLog(@"0000000---------%@",NSStringFromClass([[self topViewController] class]));
  //    if ([NSStringFromClass([[self topViewController] class]) isEqualToString:@"FirstViewController"]) {
         
  //        //横屏
  //        return UIInterfaceOrientationMaskLandscapeRight;
  //    }
  //    //竖屏
  //    return UIInterfaceOrientationMaskPortrait;
  
      NSUInteger orientations = UIInterfaceOrientationMaskAllButUpsideDown;
  
      if(self.window.rootViewController){
          //取出当前显示的控制器
          UIViewController *presentedViewController = [self topViewControllerWithRootViewController:self.window.rootViewController];
          //按当前控制器支持的方向确定旋转方向(将旋转方向重新交给每个控制器自己控制)
          NSLog(@"%s, line = %d",__FUNCTION__,__LINE__);
          orientations = [presentedViewController supportedInterfaceOrientations];
      }
  
      return orientations;
  }
  //获取界面最上层的控制器
  //- (UIViewController*)topViewController {
         
  //    NSLog(@"%s, line = %d",__FUNCTION__,__LINE__);
  //    return [self topViewControllerWithRootViewController:[UIApplication sharedApplication].keyWindow.rootViewController];
  //}
  //一层一层的进行查找判断
  - (UIViewController*)topViewControllerWithRootViewController:(UIViewController*)rootViewController {
      NSLog(@"%s, line = %d",__FUNCTION__,__LINE__);
      if ([rootViewController isKindOfClass:[UITabBarController class]]) {
  
          UITabBarController* tabBarController = (UITabBarController*)rootViewController;
          NSLog(@"Tabbar:%@",NSStringFromClass([tabBarController.selectedViewController class]));
  
          return [self topViewControllerWithRootViewController:tabBarController.selectedViewController];
      } else if ([rootViewController isKindOfClass:[UINavigationController class]]) {
  
          UINavigationController* nav = (UINavigationController*)rootViewController;
          NSLog(@"nav:%@",NSStringFromClass([nav.visibleViewController class]));
          return [self topViewControllerWithRootViewController:nav.visibleViewController];
      } else if (rootViewController.presentedViewController) {
          NSLog(@"present:%@",NSStringFromClass([rootViewController.presentationController class]));
          UIViewController* presentedViewController = rootViewController.presentedViewController;
          return [self topViewControllerWithRootViewController:presentedViewController];
      } else {
          NSLog(@"root:%@",rootViewController);
          return rootViewController;
      }
  }
  

  代码中通过 -(UIInterfaceOrientationMask)application:(UIApplication *)application supportedInterfaceOrientationsForWindow:(UIWindow *)window 方法将控制器交给自己控制，该方法默认值为Info.plist中配置的Supported interface orientations项的值。

• 第2步：在各控制器设置支持的方向

  //是否允许旋转(默认允许)
  - (BOOL)shouldAutorotate {
    return YES;
  }
  
  - (UIInterfaceOrientationMask)supportedInterfaceOrientations{
    //允许旋转的方向
    return UIInterfaceOrientationMaskAll;
  }

  其中- supportedInterfaceOrientations 方法在 iPad 中默认取值为 UIInterfaceOrientationMaskAll，即默认支持所有屏幕方向；而 iPhone 跟 iPod Touch 的默认取值为 UIInterfaceOrientationMaskAllButUpsideDown，即支持除竖屏向下以外的三个方向。
  在设备屏幕旋转时，系统会调用 - shouldAutorotate 方法检查当前界面是否支持旋转，只有 - shouldAutorotate返回 YES 的时候，- supportedInterfaceOrientations 方法才会被调用，以确定是否需要旋转界面。
  这个是 TabbarController 中设置的,它会影响关联的 UIViewController 的支持方向，需要在 UIViewController 中进一步设置

  //此方法来控制能否横竖屏 控制锁屏
  - (UIInterfaceOrientationMask)supportedInterfaceOrientations {
      NSLog(@"%s, line = %d",__FUNCTION__,__LINE__);
      UIInterfaceOrientationMask inter;
      if (_lockScreen) {
          switch (_lockOrientation) {
              case 1:
                  inter = UIInterfaceOrientationMaskPortrait;
                  break;
              case 2:
                  inter = UIInterfaceOrientationMaskPortraitUpsideDown;
                  break;
              case 3:
                  inter = UIInterfaceOrientationMaskLandscapeRight;
                  break;
              case 4:
                  inter = UIInterfaceOrientationMaskLandscapeLeft;
                  break;
              default:inter = UIInterfaceOrientationMaskAll;
                  break;
          }
      } else {
          inter = UIInterfaceOrientationMaskAll;
      }
      //支持全部方向
      return inter;
  }

• 第3步：强制转换控制器方向

  - (void)setInterOrientation:(UIInterfaceOrientation)orientation {
  
      if ([[UIDevice currentDevice] respondsToSelector:@selector(setOrientation:)]) {
          SEL selector             = NSSelectorFromString(@"setOrientation:");
          NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:[UIDevice instanceMethodSignatureForSelector:selector]];
          [invocation setSelector:selector];
          [invocation setTarget:[UIDevice currentDevice]];
          int val                  = orientation;
          // 从2开始是因为0 1 两个参数已经被selector和target占用
          [invocation setArgument:&val atIndex:2];
          [invocation invoke];
      }
  }

  这样就可以完成横竖屏的切换。

2、屏幕旋转相应改变视图位置

这里先扩展UIDeviceOrientation & UIInterfaceOrientation的知识

• UIDeviceOrientation 设备的物理方向
  UIDeviceOrientation即我们手持的移动设备的Orientation，是一个三围空间,有六个方向,通过[UIDevice currentDevice].orientation获取当前设备的方向。

  typedef NS_ENUM(NSInteger, UIDeviceOrientation) {
    UIDeviceOrientationUnknown,
    UIDeviceOrientationPortrait,            
    UIDeviceOrientationPortraitUpsideDown,  // Device oriented vertically, home button on the top 竖屏向下，即头在下，Home 键在上
    UIDeviceOrientationLandscapeLeft,       // Device oriented horizontally, home button on the right 横屏头在左，Home键在右
    UIDeviceOrientationLandscapeRight,      // Device oriented horizontally, home button on the left  横屏头在右，Home键在左
    UIDeviceOrientationFaceUp,              // Device oriented flat, face up
    UIDeviceOrientationFaceDown             // Device oriented flat, face down
  } ;

• UIInterfaceOrientation界面的显示方向

  UIInterfaceOrientation即我们看到的视图的Orientation，可以理解为statusBar所在的方向，是一个二维空间，有四个方向, 通过[UIApplication sharedApplication].statusBarOrientation即状态栏的方向获取当前界面方向。

  // Note that UIInterfaceOrientationLandscapeLeft is equal to   UIDeviceOrientationLandscapeRight (and vice versa).
  // This is because rotating the device to the left requires rotating the content to the right.
  typedef NS_ENUM(NSInteger, UIInterfaceOrientation) {
    UIInterfaceOrientationUnknown            = UIDeviceOrientationUnknown,
    UIInterfaceOrientationPortrait           = UIDeviceOrientationPortrait,
    UIInterfaceOrientationPortraitUpsideDown = UIDeviceOrientationPortraitUpsideDown,
    UIInterfaceOrientationLandscapeLeft      = UIDeviceOrientationLandscapeRight,
    UIInterfaceOrientationLandscapeRight     = UIDeviceOrientationLandscapeLeft
  } 

• UIInterfaceOrientationMask支持的方向

  // iOS 6 之后用于控制界面的枚举值
  typedef NS_OPTIONS(NSUInteger, UIInterfaceOrientationMask) {
  UIInterfaceOrientationMaskPortrait = (1 << UIInterfaceOrientationPortrait),
  UIInterfaceOrientationMaskLandscapeLeft = (1 << UIInterfaceOrientationLandscapeLeft),
  UIInterfaceOrientationMaskLandscapeRight = (1 << UIInterfaceOrientationLandscapeRight),
  UIInterfaceOrientationMaskPortraitUpsideDown = (1 << UIInterfaceOrientationPortraitUpsideDown),
  UIInterfaceOrientationMaskLandscape = (UIInterfaceOrientationMaskLandscapeLeft | UIInterfaceOrientationMaskLandscapeRight),
  UIInterfaceOrientationMaskAll = (UIInterfaceOrientationMaskPortrait | UIInterfaceOrientationMaskLandscapeLeft | UIInterfaceOrientationMaskLandscapeRight | UIInterfaceOrientationMaskPortraitUpsideDown),
  UIInterfaceOrientationMaskAllButUpsideDown = (UIInterfaceOrientationMaskPortrait | UIInterfaceOrientationMaskLandscapeLeft | UIInterfaceOrientationMaskLandscapeRight),
  }

  由上可以发现：

  1. iOS 6 及之后版本使用的UIInterfaceOrientationMask类型来控制屏幕屏幕方向，该类型也新增加了几个枚举取值，可用一个枚举取值来代表多个屏幕方向，使用起来更方便。
  2. 注意在UIInterfaceOrientation中有注释 Note that UIInterfaceOrientationLandscapeLeft is equal to UIDeviceOrientationLandscapeRight (and vice versa).
     This is because rotating the device to the left requires rotating the content to the right ，大意是界面的左转相当于设备的右转，如果设备向左转时就需要内容（即界面）向右转。即：
     UIInterfaceOrientationLandscapeLeft = UIDeviceOrientationLandscapeRight
UIInterfaceOrientationLandscapeRight = UIDeviceOrientationLandscapeLeft
     下面还会举例说明。

其实UIDeviceOrientation与UIInterfaceOrientation是两个互不相干的属性，通常情况下会一起出现，在这里正好利用此特性在屏幕旋转后进行重新布局。

4、锁屏

锁屏时，不管系统锁屏是否关闭、Push 或 Present 返回后，界面依然保持不变。

• 第1步：监听 UIDeviceOrientationDidChangeNotification状态

  //监听设备旋转 改变 视图 对应位置
  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(deviceOrientationDidChange) name:UIDeviceOrientationDidChangeNotification object:nil];
  
  //用来控制横竖屏时调整视图位置
  - (void)deviceOrientationDidChange
  {
    [self isPortrait]; 
  }

• 第2步：重新布局

  if (_interOrientation == UIInterfaceOrientationPortrait || _interOrientation == UIInterfaceOrientationPortraitUpsideDown) {
          self.top.constant = 145;
          self.bottom.constant = 210;
  
      } else if (_interOrientation == UIInterfaceOrientationLandscapeRight || _interOrientation == UIInterfaceOrientationLandscapeLeft) {
          self.top.constant = 40;
          self.bottom.constant = 50;
      }

  例如：竖屏转横屏
  界面竖屏UIInterfaceOrientationPortrait ->横屏UIInterfaceOrientationLandscapeRight，设备方向UIDeviceOrientationPortrait->UIDeviceOrientationLandscapeLeft,在设备发生变化这个过程触发UIDeviceOrientationDidChangeNotification监听，然后进行重新布局。

3、旋转时状态栏的隐藏与显示

• 这里只记述旋转时状态栏的变化，由竖屏想横屏变化时状态栏会消失。

  //在需要的`UIViewController`设置是否隐藏
  - (BOOL)prefersStatusBarHidden {
  NSLog(@"%s, line = %d",__FUNCTION__,__LINE__);
  return NO;
  }

4、锁屏

锁屏时，不管系统锁屏是否关闭、Push 或 Present 返回后，界面依然保持不变。

• 第1步：设置锁屏

  - (IBAction)lockAction:(UIButton *)sender {
      if (_lockScreen) {
  
          _lockScreen = NO;
          [sender setTitle:@"锁定屏幕" forState:UIControlStateNormal];
      } else {
          _lockScreen = YES;
  
          [sender setTitle:@"解开屏幕" forState:UIControlStateNormal];
      }
      _lockOrientation = _interOrientation;
  }

• 第2步：绕过强转

  - (void)interfaceOrientation:(UIInterfaceOrientation)orientation
  {
  
      [self isPortrait];
      //锁屏情况下 不旋转
      if (!_lockScreen) {
          [self setInterOrientation:orientation];
      }

• 第3步：针对 Push 或 Present 返回后

  - (void)viewWillAppear:(BOOL)animated {
  
      if (_lockScreen) {
          //记录返回时的界面状态
          [self setInterOrientation:_lockOrientation];
      } else {
        [self isPortrait];
      }
  }

5、 针对特定UIViewController方向的支持

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

        if ([NSStringFromClass([[self topViewController] class]) isEqualToString:@"FirstViewController"]) {
            //横屏
            return UIInterfaceOrientationMaskLandscapeRight;
        }
        //竖屏
        return UIInterfaceOrientationMaskPortrait;
    }

最后的献上GitHub代码，还有2个小的 bug ，有兴趣的朋友欢迎来探讨。

- 参考文章：

iOS 屏幕旋转问题总结
iOS 屏幕方向那点事儿