Xcode9 2018年最新关于app编写中，大部分界面强制竖屏，个别界面使用横屏完美解决

第一步：

8180BBD0-9D78-4110-980A-F1D0F2651D27.png

第二步：
在AppDelegate里面添加方法2个

• (UIViewController *)getViewController

{

UIViewController *appRootVC = [UIApplication sharedApplication].keyWindow.rootViewController;

UIViewController *topVC = appRootVC;

if (topVC.presentedViewController) {
    
    topVC = topVC.presentedViewController;
    
}

return topVC;

}

//锁定用户手机APP为竖屏模式

• (NSUInteger)application:(UIApplication *)application supportedInterfaceOrientationsForWindow:(UIWindow *)window
  {
  //这里是你需要横屏的部分控制器 ，我这里是3个控制器必须为横屏，其余全部是横屏
  UIViewController * vc = [self getViewController];
  if ([vc isKindOfClass:[DYMarkingVC class]]|| [vc isKindOfClass:[DYMarkingQuestionVC class]] || [vc isKindOfClass:[DYMarkingArbitrationVC class]] ) {
  return UIInterfaceOrientationMaskAll;
  }else{
  return UIInterfaceOrientationMaskPortrait;
  }

}

第三步：
具体需要横屏的控制器添加下面方法

pragma mark 强制横屏(针对present方式)

• (BOOL) shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation {
  return (UIInterfaceOrientationLandscapeRight | UIInterfaceOrientationLandscapeLeft);
  }

• (UIInterfaceOrientationMask)supportedInterfaceOrientations {
  return UIInterfaceOrientationMaskLandscapeRight | UIInterfaceOrientationMaskLandscapeLeft;
  }

//必须有
-(UIInterfaceOrientation)preferredInterfaceOrientationForPresentation{
return UIInterfaceOrientationLandscapeRight;
}

第四步：
在竖屏A prensent到横屏B中，所有A都要添加代码
//强制转屏

• (void)interfaceOrientation:(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];
  }
  }

-(void)viewWillAppear:(BOOL)animated{
[super viewWillAppear:YES];

[self interfaceOrientation:UIInterfaceOrientationPortrait];

}

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