从应用委托中获取当前视图控制器 [英] Get the current view controller from the app delegate

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-从应用委托(modal是可能的)需要帮助.

i am new to ios. I need to know the current view controller from app delegate.. i have no idea about this and i don't knowto implement this. i am using this code toimplemnt this but it return null values. I followed this link- Get current view controller from the app delegate (modal is possible) need help.

推荐答案

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:

This is what I use for finding the current view controller that the user is most likely interacting with:

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:

Then whenever I need the current view controller from anywhere in the app simply use:

[UIViewController currentViewController]

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