title: Use prepareForSegue:Sender when switching VC in UITabBarController
body: <p>I have googled far and wide, but everything is extremely confusing. I need it so when the tab bar gets switched to a different view controller, is there a method that gets called when the view controllers are about to switch, get the destination controller and set some variables to add some annotations to a MKMapView. How can I do this?</p>