从应用委托中获取当前视图控制器答案

【问题标题】：Get the current view controller from the app delegate从应用委托中获取当前视图控制器
【发布时间】：2014-09-09 14:22:15
【问题描述】：

我是 ios 新手。我需要从应用程序委托中知道当前的视图控制器。我对此一无所知，也不知道如何实现它。我正在使用此代码来实现这一点，但它返回空值。我跟着这个链接- Get current view controller from the app delegate (modal is possible) 需要帮助。

【问题讨论】：

你在使用导航控制器吗？否则发布您的代码以更好地理解

标签： ios objective-c delegates appdelegate

【解决方案1】：

这是我用来查找用户最有可能与之交互的当前视图控制器的方法：

UIViewController+Utils.h

#import <UIKit/UIKit.h>

@interface UIViewController (Utils)

+(UIViewController*) currentViewController;

@end

UIViewController+Utils.m

#import "UIViewController+Utils.h"

@implementation UIViewController (Utils)

+(UIViewController*) findBestViewController:(UIViewController*)vc {

    if (vc.presentedViewController) {

        // Return presented view controller
        return [UIViewController findBestViewController:vc.presentedViewController];

    } else if ([vc isKindOfClass:[UISplitViewController class]]) {

        // Return right hand side
        UISplitViewController* svc = (UISplitViewController*) vc;
        if (svc.viewControllers.count > 0)
            return [UIViewController findBestViewController:svc.viewControllers.lastObject];
        else
            return vc;

    } else if ([vc isKindOfClass:[UINavigationController class]]) {

        // Return top view
        UINavigationController* svc = (UINavigationController*) vc;
        if (svc.viewControllers.count > 0)
            return [UIViewController findBestViewController:svc.topViewController];
        else
            return vc;

    } else if ([vc isKindOfClass:[UITabBarController class]]) {

        // Return visible view
        UITabBarController* svc = (UITabBarController*) vc;
        if (svc.viewControllers.count > 0)
            return [UIViewController findBestViewController:svc.selectedViewController];
        else
            return vc;

    } else {

        // Unknown view controller type, return last child view controller
        return vc;

    }

}

+(UIViewController*) currentViewController {

    // Find best view controller
    UIViewController* viewController = [UIApplication sharedApplication].keyWindow.rootViewController;
    return [UIViewController findBestViewController:viewController];

}

@end

然后，每当我需要应用程序中任何地方的当前视图控制器时，只需使用：

[UIViewController currentViewController]

【讨论】：

【解决方案2】：

这里有一些 swift 中的类/静态函数，我保留在 Utility 类中，可以帮助您：

// Returns the most recently presented UIViewController (visible)
class func getCurrentViewController() -> UIViewController? {

    // If the root view is a navigation controller, we can just return the visible ViewController
    if let navigationController = getNavigationController() {

        return navigationController.visibleViewController
    }

    // Otherwise, we must get the root UIViewController and iterate through presented views
    if let rootController = UIApplication.shared.keyWindow?.rootViewController {

        var currentController: UIViewController! = rootController

        // Each ViewController keeps track of the view it has presented, so we
        // can move from the head to the tail, which will always be the current view
        while( currentController.presentedViewController != nil ) {

            currentController = currentController.presentedViewController
        }
        return currentController
    }
    return nil
}

// Returns the navigation controller if it exists
class func getNavigationController() -> UINavigationController? {

    if let navigationController = UIApplication.shared.keyWindow?.rootViewController  {

        return navigationController as? UINavigationController
    }
    return nil
}

【讨论】：

我通过修改成功地使用了它来编译它。需要重新安排。
@alaxandermiller，我怎样才能使用这些来获取视图控制器名称作为字符串？

【解决方案3】：

jjv360 的最佳答案的 Swift 版本，（我去掉了一些多余的返回，我觉得 Swift 的可读性更好）

func getCurrentViewController(_ vc: UIViewController) -> UIViewController? {
    if let pvc = vc.presentedViewController {
        return getCurrentViewController(pvc)
    }
    else if let svc = vc as? UISplitViewController, svc.viewControllers.count > 0 {
        return getCurrentViewController(svc.viewControllers.last!)
    }
    else if let nc = vc as? UINavigationController, nc.viewControllers.count > 0 {
        return getCurrentViewController(nc.topViewController!)
    }
    else if let tbc = vc as? UITabBarController {
        if let svc = tbc.selectedViewController {
            return getCurrentViewController(svc)
        }
    }
    return vc
}

来自您的 AppDelegate，

    guard let rvc = self.window?.rootViewController else {
        return
    }
    if let vc = getCurrentViewController(rvc) {
        // do your stuff here
    }

【讨论】：

【解决方案4】：

这帮助我找到了可见的视图控制器。我搜索了现有的方法，但没有找到。所以我自己写了一个。

-(id)getCurrentViewController
{
    id WindowRootVC = [[[[UIApplication sharedApplication] delegate] window] rootViewController];

    id currentViewController = [self findTopViewController:WindowRootVC];

    return currentViewController;
}

-(id)findTopViewController:(id)inController
{
    /* if ur using any Customs classes, do like this.
     * Here SlideNavigationController is a subclass of UINavigationController.
     * And ensure you check the custom classes before native controllers , if u have any in your hierarchy.
    if ([inController isKindOfClass:[SlideNavigationController class]])
    {
        return [self findTopViewController:[inController visibleViewController]];
    }
    else */
    if ([inController isKindOfClass:[UITabBarController class]])
    {
        return [self findTopViewController:[inController selectedViewController]];
    }
    else if ([inController isKindOfClass:[UINavigationController class]])
    {
        return [self findTopViewController:[inController visibleViewController]];
    }
    else if ([inController isKindOfClass:[UIViewController class]])
    {
        return inController;
    }
    else
    {
        NSLog(@"Unhandled ViewController class : %@",inController);
        return nil;
    }
}

和样品使用：

-(void)someMethod
{
    id currentVC = [self getCurrentViewController];
        if (currentVC)
        {
            NSLog(@"currentVC :%@",currentVC);
        }
}

【讨论】：

【解决方案5】：

这取决于您如何设置用户界面。如果以这种方式设置，您可能会获取您的 rootViewController 并在层次结构中移动。

UIViewController *vc = self.window.rootViewController;

【讨论】：

我以这种方式获取视图控制器名称 - 最后一个视图控制器是 vc== 但我想要视图控制器的名称。
如果你关注这个并且你想要控制器的名称然后尝试 id vc = self.window.rootViewController; NSLog(@"控制器名称: %@", [vc 类]);

【解决方案6】：

UIViewController* actualVC = [anyViewController.navigationController.viewControllers lastObject];

【讨论】：

【解决方案7】：

我得到根控制器，然后遍历提供的 VC：

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

while (current.presentedViewController) {
    current = current.presentedViewController;
}
//now you can use current, for example to present an alert view controller:
[current presentViewController:alert animated:YES completion:nil];

【讨论】：

【解决方案8】：

|*|从 Navigation View Controller 获取 Visible View Controller

let NavVccVar = UIApplication.sharedApplication().keyWindow?.rootViewController as! UINavigationController
let ShnSrnVar = NavVccVar.visibleViewController

|*|从可见视图控制器呈现

let NavVccVar = UIApplication.sharedApplication().keyWindow?.rootViewController as! UINavigationController
NavVccVar.visibleViewController!.presentViewController(NamVccVar, animated: true, completion: nil)

【讨论】：

【解决方案9】：

这是我尝试过的最好的解决方案

+ (UIViewController*) topMostController
{
    UIViewController *topController = [UIApplication sharedApplication].keyWindow.rootViewController;

    while (topController.presentedViewController) {
        topController = topController.presentedViewController;
    }

    return topController;
}

【讨论】：

【解决方案10】：

Swift 解决方案 对于 iOS 13+ 我们有SceneDelgate 和多个窗口，所以您需要使用以下代码：

private func getCurrentViewController() -> UIViewController? {
    if let rootViewController = UIApplication.shared.windows.first?.rootViewController {
        
        if let presentedViewController = rootViewController.presentedViewController {
            return presentedViewController
        }
        
        return rootViewController
    }
    
    return nil
}

【讨论】：

【解决方案11】：

我正在使用此代码-

//in AppDelegate:

@interface AppDelegate()

{

    id lastViewController;

}


@implementation AppDelegate

-(BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:
(NSDictionary *)launchOptions

{

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleCurrentViewController) name:@"CurrentViewController" object:nil];


}

-(void)handleCurrentViewController:(NSNotification *)notification
 {

    if([[notification userInfo] objectForKey:@"lastViewController"])
   {

        lastViewController = [[notification userInfo] objectForKey:@"lastViewController"];

    }
}

-(void)applicationDidEnterBackground:(UIApplication *)application
{  

    NSLog(@"last view controller is %@", [(UIViewController *)lastViewController class]);

}

@end

//在您要检测的每个 ViewController 中

@implementation SomeViewController

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

    [[NSNotificationCenter defaultCenter] postNotificationName:@"CurrentViewController" object:nil userInfo:[NSDictionary dictionaryWithObjectsAndKeys:self, @"lastViewController", nil]];

}

【讨论】：

【解决方案12】：

我发现了这一点，它适用于所有类型的 segue 和视图控制器。它非常简单和简短，这很好。

+(UIViewController*) getTopController{ UIViewController *topViewController = [UIApplication sharedApplication].keyWindow.rootViewController;
while (topViewController.presentedViewController) {
    topViewController = topViewController.presentedViewController;
}

return topViewController; }

【讨论】：