CODEWITHSUNDEEP
iphone
Anson MacKeracher
Anson MacKeracher

Reputation: 472

How do I remove a view controller from my view hierarchy?

My app has a welcome screen that can only be shown in portrait mode. After the user has tapped through the welcome screen I'd like to show another screen that can be used in both portrait mode and landscape.

I have set up a view controller that implements shouldAutorotateToInterfaceOrientation: returning YES only for UIInterfaceOrientationPortrait, and I add the view to the window with [window addSubView:view]. I tag this view with the tag 1.

When the user taps through the welcome view and the app moves on to the new view I do:

[[window viewWithTag:1] removeFromSuperView];
[window addSubView:myViewController.view];

Where myViewController is an instance of the 2nd view's view controller (that handles the shouldAutorotateToInterfceOrientation method properly).

Now when I rotate, it still calls shouldAutorotateToInterfceOrientation on the original view's view controller, and does not call it on the new view's view controller.

This note from Apple says that only one view controller will get rotation notifications; however, I have removed the other view controller.

What am I doing wrong?

Upvotes: 0

Views: 1060

Answers (3)

Ken Joyner
Ken Joyner

Reputation: 921

I wrote up a quick test that shows what you are trying to do should work. Here are the basics I did:

Create two view controllers. App starts with the first view controller being set in the AppDelegate into an instance variable viewController through NIB files. It is then added to the window as you have written.

I then setup an action that when called (could be a Timer, button on first view controller, etc.) that performed the following:

Remove view using [self.viewController removeFromSuperview]. This is different than the way you have done with the tag.

Created second view controller and assigned it to self.viewController.

Added to window like you have specified.

Not sure what is incorrect with your code. I would guess that perhaps the first view wasn't really being removed.

Upvotes: 1

Magnus
Magnus

Reputation: 2060

as the note you link to state:

Only the first view controller added to UIWindow will rotate.

So put a flag that makes sure that shouldAutorotateToInterfceOrientation returns NO until the user have dismissed the screen - and then returns YES afterwards. This is a simple and working solution - however, from a code readability point it might be confusing that a "dismissed" view actually controll the rotation.

Personally; my experience is that it's not really worthwhile having some views rotating and some don't - and users tend to don't like it.

happy coding

Upvotes: 1

Moszi
Moszi

Reputation: 3236

actually that note doesn't say that "only one view controller will get the notifications" but instead it says that "Only the first view controller added to UIWindow will rotate.". So this might be the problem.

To resolve it, i would say to always have a view added to your window (call it permanent), and add your welcome screen and the next views to this permanent view.

Hope this helps.

Upvotes: 1

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