iOS屏幕旋转与锁屏的示例代码

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

iOS-旋转.gif

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：

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。

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。

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。

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