Changing the colour of Navigation Controller bottom toolBar

I am trying to change the colour of the bottom bar of my Navigation Controller. I have managed to change the top NavBar in my appdelegate by adding

[[UINavigationBar appearance] setBarTintColor:[UIColor colorWithRed:0.688 green:0.437 blue:0.794 alpha:1.0]];

I want to apply this to the bottom bar also.