問題描述

我需要一個根視圖控制器的實例.

I need an instance of root view controller.

我嘗試了這些方法:

UIViewController *rootViewController = (UIViewController*)[[[UIApplication sharedApplication] keyWindow] rootViewController];

返回:null:

當我嘗試獲取控制器數組時:

Also when I try to get an array of controllers:

NSArray *viewControllers = self.navigationController.viewControllers;

它只返回一個控制器，但它不是我的根視圖控制器.

It returns only one controller, but it isn't my root view controller.

如果我嘗試從導航控制器中獲取:

If I try to take from navigation controller:

UIViewController *root = (UIViewController*)[self.navigationController.viewControllers objectAtIndex:0];

返回:null:

任何想法為什么?我還能嘗試獲取根視圖控制器的實例嗎?

Any ideas why? What else could I try to get an instance of my root view controller?

謝謝.

推薦答案

如果您嘗試訪問您在 appDelegate 中設置的 rootViewController.試試這個:

if you are trying to access the rootViewController you set in your appDelegate. try this:

Objective-C

YourViewController *rootController = (YourViewController*)[[(YourAppDelegate*)
                                   [[UIApplication sharedApplication]delegate] window] rootViewController];

斯威夫特

let appDelegate  = UIApplication.sharedApplication().delegate as AppDelegate
let viewController = appDelegate.window!.rootViewController as YourViewController

斯威夫特 3

let appDelegate  = UIApplication.shared.delegate as! AppDelegate
let viewController = appDelegate.window!.rootViewController as! YourViewController

斯威夫特 4 &4.2

let viewController = UIApplication.shared.keyWindow!.rootViewController as! YourViewController

斯威夫特 5 &5.1 &5.2

let viewController = UIApplication.shared.windows.first!.rootViewController as! YourViewController

這篇關于如何獲取根視圖控制器?的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！