从应用程序委托获取当前视图控制器

Question

我是ios的新手.我需要从app委托知道当前的视图控制器..我不知道这个,我不知道实现这个.我正在使用此代码来实现此功能,但它返回null值.我按照这个链接 - 从应用程序委托获取当前视图控制器(模态是可能的) 需要帮助.

Answer 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:

的UIViewController + Utils.h

#import <UIKit/UIKit.h>

@interface UIViewController (Utils)

+(UIViewController*) currentViewController;

@end

的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,只要我需要应用程序中任何位置的当前视图控制器,只需使用:

[UIViewController currentViewController]

Answer 2

这里有swift中的一些类/静态函数,我保存在Utility类中,可以帮助你:

// 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.sharedApplication().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.sharedApplication().keyWindow?.rootViewController  {

        return navigationController as? UINavigationController
    }
    return nil
}

Answer 3

这取决于您如何设置 UI。如果以这种方式设置，您可以获取您的 rootViewController 并在层次结构中移动。

UIViewController *vc = self.window.rootViewController;

Answer 4

这有助于我找到可见的视图控制器.我搜索了现有的方法,但没有找到任何方法.所以我写了自己的自定义.

-(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;
    }
}

样品使用:

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

Answer 5

jjv360 的 Swift 版本很好的答案，（我去掉了一些多余的回报，我认为 Swift 更具可读性）

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
    }