目标C：如何从appdelegate呈现模态视图控制器？ [英] Objective C: How to present modal view controller from appdelegate?

问题描述

我在申请的appdelegate。如何在didfinishlaunching方法中添加模态视图控制器？

I am in the appdelegate of my application. How can I add a modal view controller in the "didfinishlaunching" method?

我尝试了以下但是没有工作

I tried the following but did not work

SomeViewController *vc = [[SomeViewController alloc]init];
[self.tabController.navigationController presentModalViewController:vc animated:NO]; 

编辑：
我将实施改为以下

I changed my implementation to the following

self.tabController.selectedViewController 
= [self.tabController.viewControllers objectAtIndex:0];
SomeViewController *vc = [[SomeViewController alloc]init];
[self.tabController.selectedViewController presentModalViewController:vc animated:NO];

我检查过选定的视图控制器不是空的...但是我还是不能获得我需要的输出。有什么我缺少的吗？

I checked that the 'selected view controller' is not null... however I am still not able to get the output I needed. Is there anything I am missing?

推荐答案

假设tabController和navigationController不是nil，applicationDidFinishLaunching可能太早显示模态视图控制器。

Assuming tabController and navigationController are not nil, the applicationDidFinishLaunching may be too soon to display the modal view controller.

1. 确保在创建窗口键并显示后放置该代码。 [self.window makeKeyAndVisible];


2. 如果这不起作用，请尝试侦听 UIWindowDidBecomeKeyNotification 用于该窗口


3. 您可以尝试使用 performSelector：withObject：afterDelay：

1. Make sure you put that code after you make the window key and visible. [self.window makeKeyAndVisible];
2. If that does not work try listening for the UIWindowDidBecomeKeyNotification for that window
3. You can try delaying presentation of that modal a few seconds using performSelector:withObject:afterDelay:

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