About self.view.window dynamically add tabbar problem

Downloading a dynamic tabbar routines, inherited a uiviewcontrol's,
Routine xib view in inheritance is uiwindow finally added code for
self.view.window.rootViewController = dynamic tabbar view controller;

Show me how it does not come out in uiview by addsubview the "Dynamic tabbar view controller. View" added nor
Also self.view.window is always null value, I by creating uiwindow as its child does not show

Feeling into the alley, and no information is good to check, please enlighten me, thank you!
Reply:
self.view.window is the value has been null, this view will prove that you do not add to the app's keyWindow.

You look at the initial view appdelegate Which, I mean, what window the RootViewController is. Then add to it a try.
Reply:
self.window.rootViewController = dynamic tabbar view controller;
Reply:
Indeed, what verification rootViewController