Advantages, problems, examples of adding another UIWindow to an iOS app?

Question

Recently I\'ve been wondering about the fact that that an iOS app only has one UIWindow. It does not seem to be an issue to create another UIWindow

Answer 1

Starting with Rob's answer I played around a bit and would like to write down some notes for others trying to get information on this topic:

• It is not a problem at all to add another UIWindow. Just create one and makeKeyAndVisible. Done.
• Remove it by making another window visible, then release the one you don't need anymore.
• The window that is "key" receives all the keyboard input.
• UIWindow covers everything, even modals, popovers, etc. Brilliant!
• UIWindow is always portrait implicitly. It does no rotate. You'll have to add a controller as the new window's root controller and let that handle rotation. (Just like the main window)
• The window's level determines how "high" it gets displayed. Set it to UIWindowLevelStatusBar to have it cover everything. Set its hidden property to NO.
• A 2nd UIWindow can be used to bring views on the screen that float on top of everything. Without creating a dummy controller just to embed that in a UIPopoverController.
• It can be especially useful on iPhone where there is no popover controller but where you might want to mimic something like it.
• And yes, it solved of course my problem: if the app resigns activation, add a cover window over whatever is currently shown to prevent iOS from taking a screenshot of your app's current content.