UIRectEdgeNone makes NavigationBar and Tabbar darker

It probably means that the there's nothing to show below the translucent tab bar. Set the tab bar translucent property to NO

@rounak is right, maybe setting the tab or nav bar's translucency to NO tells iOS not to try to put another tab or nav bar under the current one, which makes it darker.

In the viewDidLoad, add this:

self.navigationController.navigationBar.translucent = NO; // if you have a nav

self.tabBarController.tabBar.translucent = NO; // if you have a tab