how to change uiviewcontroller title independent of tabbar item title
Solution 1:
It sounds like you want the title in the navigation bar to change but not the one in the tabbar. This should do that.
[self.navigationItem setTitle:@"my title"];
Swift:
self.navigationItem.title = "My Title"
Solution 2:
So for those who still don't get it (like me)
self.navigationItem.title = @"my title"; sets navigation bar title.
self.tabBarItem.title = @"my title"; sets tab bar title.
self.title = @"my title"; sets both of these.