iPad: Launch MainWindow.xib's primary view without using InterfaceBuilder confi

I get really confused using InterfaceBuilder to setup the main window xib file's primary controller view. Is there a good example or simple way to launch the ViewController 开发者_如何转开发I want to show by default in the Application Delegate instead of setting it up in InterfaceBuilder's MainWindow.xib file?

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you can show your view by code as

FirstViewController *fvc = [[FirstViewController alloc] init];

[window addSubView:fvc];