Here is my tab bar:

The following image shows the program being run an
For Swift 4.0, it's now changed as:
tabBarItem.setTitleTextAttributes([NSAttributedStringKey.foregroundColor: UIColor.gray], for: .normal)
tabBarItem.setTitleTextAttributes([NSAttributedStringKey.foregroundColor: UIColor.blue], for: .selected)
You don't have to subclass the UITabBarItem if your requirement is only to change the text color. Just put the above code inside your view controller's viewDidLoad function.
For global settings change tabBarItem to UITabBarItem.appearance().