code alignment
Initialize the tab bar in initWithNibName

- Why did we create our tab item in initWithNibName:bundle:? We want to create the tabBarItem() as soon as the controller exists, regardless of whether its view has been created yet. UITabBarController will load the views only when absolutely necessary, so if you wait to create the tab item in viewDidLoad(), then some controllers’ items might not be set when the app is done launching.
rename controller to a more describing one.
build