从ViewController (storyboard)调用NavigationController (xib)

I'm normally just use storyboard for my iOS, but needed to integrate an SDK which does not use storyboard, rather xib. My initial view controller is from storyboard, and when a button is pushed (IBAction), I would like it to go to the xib view controller, but not sure how programmatically to do so. Here is my AppDelegate:I'm normally just use storyboard for my iOS, bu