     required public init(coder aDecoder: NSCoder) {
         _tabBarHidden = false
         tabBar = ElloTabBar()
-        previousTab = selectedTab
 
         super.init(coder: aDecoder)
     }

    case Stream
    case Profile
    case Post
}

public class ElloTabBarController: UIViewController, HasAppController {

        set { setTabBarHidden(newValue, animated: false) }
    }

    public private(set) var previousTab: ElloTab = .DefaultTab
    public var selectedTab: ElloTab = .DefaultTab {
        willSet {
            if selectedTab != previousTab {
                previousTab = selectedTab
            }
        }
        didSet {
            updateVisibleViewController()
            tabBar.selectedItem = selectedViewController.tabBarItem
        }
