来自AppDelegate的当前视图控制器？

Question

有没有办法从AppDelegate获取当前视图控制器？我知道有rootViewController,但这不是我想要的.

Answer 1

如果你的应用程序的根视图控制器是a,UINavigationController你可以这样做:

((UINavigationController*)appDelegate.window.rootViewController).visibleViewController;

同样,如果是a,UITabBarController你可以这样做:

((UITabBarController*)appDelegate.window.rootViewController).selectedViewController;

当然,像这样的显式铸造很脏.更好的方法是使用强类型捕获引用.

Answer 2

这可能有所帮助

- (UIViewController *)topViewController{
  return [self topViewController:[UIApplication sharedApplication].keyWindow.rootViewController];
}

- (UIViewController *)topViewController:(UIViewController *)rootViewController
{
  if (rootViewController.presentedViewController == nil) {
    return rootViewController;
  }

  if ([rootViewController.presentedViewController isKindOfClass:[UINavigationController class]]) {
    UINavigationController *navigationController = (UINavigationController *)rootViewController.presentedViewController;
    UIViewController *lastViewController = [[navigationController viewControllers] lastObject];
    return [self topViewController:lastViewController];
  }

  UIViewController *presentedViewController = (UIViewController *)rootViewController.presentedViewController;
  return [self topViewController:presentedViewController];
}

Swift版本:

extension UIApplication {
    class func topViewController(base: UIViewController? = UIApplication.shared.keyWindow?.rootViewController) -> UIViewController? {
        if let nav = base as? UINavigationController {
            return topViewController(base: nav.visibleViewController)
        }
        if let tab = base as? UITabBarController {
            if let selected = tab.selectedViewController {
                return topViewController(base: selected)
            }
        }
        if let presented = base?.presentedViewController {
            return topViewController(base: presented)
        }
        return base
    }
}

取自:https: //gist.github.com/snikch/3661188

Answer 3

如果你有UINavigationController到appDelegate然后使用它的属性topViewController或visibleViewController

Answer 4

进行扩展:

extension UIApplication {
    class func topViewController(base: UIViewController? = UIApplication.sharedApplication().keyWindow?.rootViewController) -> UIViewController? {
        if let nav = base as? UINavigationController {
            return topViewController(nav.visibleViewController)
        }
        if let tab = base as? UITabBarController {
            let moreNavigationController = tab.moreNavigationController

            if let top = moreNavigationController.topViewController where top.view.window != nil {
                return topViewController(top)
            } else if let selected = tab.selectedViewController {
                return topViewController(selected)
            }
        }
        if let presented = base?.presentedViewController {
            return topViewController(presented)
        }
        return base
    }
}

用法:

if let rootViewController = UIApplication.topViewController() {
    //do sth with root view controller
}

Answer 5

获取appDelegate对象:

MyAppDelegate *tmpDelegate = (MyAppDelegate *)[[UIApplication sharedApplication] delegate];

由于beryllium建议您可以使用UINavigationController的属性来访问当前的视图控制器.

所以代码看起来像:

id myCurrentController = tmpDelegate.myNavigationController.topViewController;

要么:

NSArray *myCurrentViewControllers = tmpDelegate.myNavigationController.viewControllers;

Answer 6

您可以通过查找其presentViewController从rootViewController获取当前视图控制器,如下所示:

UIViewController *parentViewController = [[[UIApplication sharedApplication] delegate] window].rootViewController;

while (parentViewController.presentedViewController != nil){
    parentViewController = parentViewController.presentedViewController;
}
UIViewController *currentViewController = parentViewController;

它适用于我.希望能帮助到你 :)

Answer 7

对于没有使用UINavigationController而是默认视图控制器为a的任何人，UIViewController您可以使用以下命令检查哪个视图控制器处于活动状态（或显示）AppDelegate：

func application(application: UIApplication, supportedInterfaceOrientationsForWindow window: UIWindow?) -> Int {
    if let rootViewController = self.window!.rootViewController {
        if let presentedViewController = rootViewController.presentedViewController {
            return presentedViewController.supportedInterfaceOrientations()
        }
    } // Else current view controller is DefaultViewController

    return Int(UIInterfaceOrientationMask.Portrait.rawValue)
}

如您所见，我正在检查当前视图控制器，以便为特定视图控制器支持不同的界面方向。对于其他有兴趣使用此方法来支持特定方法的人，应在每个需要特定方向的视图控制器中放置以下内容。

override func supportedInterfaceOrientations() -> Int {
    return Int(UIInterfaceOrientationMask.All.rawValue)
} 

注意：此代码是使用Swift 1.2编写的

Answer 8

基于AG 解决方案的Swift 4+语法中的UIApplication 扩展

public extension UIApplication {

    class func topViewController(base: UIViewController? = UIApplication.shared.keyWindow?.rootViewController) -> UIViewController? {
        if let nav = base as? UINavigationController {
            return topViewController(base: nav.visibleViewController)
        }
        if let tab = base as? UITabBarController {
            let moreNavigationController = tab.moreNavigationController

            if let top = moreNavigationController.topViewController, top.view.window != nil {
                return topViewController(base: top)
            } else if let selected = tab.selectedViewController {
                return topViewController(base: selected)
            }
        }
        if let presented = base?.presentedViewController {
            return topViewController(base: presented)
        }
        return base
    }
}

示例用法：

if let rootViewController = UIApplication.topViewController() {
     //do something with rootViewController
}