Add the login screen problem

There is now a UIViewController application, now I want to add one in this application login screen, giving the application displays the login screen when you start, but tried many ways do not work, experts have urged twelve.
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In viewdidload Riga no good?
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Did not quite understand what you say ~ ~ ~ I understand you delegate object inside the first call into your login screen then jumps to the login screen before doing those pages!
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I added in didFinishLaunchingWithOptions open the login page code slightly, or mainWindow inside plus login page line ah
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In didFinishLaunchingWithOptions (delegate in) inside join login code, after the successful landing in the call originally UIViewController
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In the delegate you want to set the page first loads the landing page, landing page viewdidload write you the information you want to display the login screen.
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Current through the interface to add in the original sub-interface to achieve, thanks for your answer