A custom tabbarViewController + custom navgationBar +custom barItem.
1.The tabbar view has 5 items and the middle item is larger than others. 2.It can set any picture for bar item image. 3.When push or pop by navgation we can set tabbar hidden or not. Defult is that ,tabbar show in the root viewController and hidden in others which pushed to. 4.Custom bar item has badage value ,when set it will show a red icon with it`s value on the tabbar item.
