AddSubview not working

Question

// Create and add a sub view CGRect viewRect = CGRectMake(0, 0, 200, 200); UIView *a_sub_view = [[UIView alloc] initWithFrame : viewRect]; [window addSubview : a_sub_view]; 

After adding the above three lines of code, xcode does not cause errors or warnings. But subview is not displayed at all. The sample program works exactly the same as before. Hope someone knows what might help.

Answer 1

It’s useful for me to set the background color so that I know where the view and the borders are.

 a_sub_view.backgroundColor = [UIColor redColor]; 

In your example, you create an empty view so that you don't see anything.

Answer 2

Window

awaiting viewing by viewcontrollers.

then you can add subitems to the current view.

so in your example use:

 [self.view addSubview:a_sub_view]; 

Answer 3

I use this to “find” a window:

 UIWindow *window = [[[UIApplication sharedApplication] delegate] window]; [window addSubview:myView]; 

This also worked for me, but it is a bit ugly:

 [self.navigationController.tabBarController.view addSubview:myView]; 

To explain the second, I had to “follow” the controllers to the “top” view. (My application has a tab bar with a navigation controller inside the current tab.)

Answer 4

If you work with iOS 5 and above, you need to do the following:

 [self.window.rootViewController.view addSubView:viewObject]; 

Answer 5

 [self.view addSubView: a_sub_view];