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Using the Document Outline, select your Navigation Bar.
In the Attributes Inspector, in the Navigation Bar group, change the Style from Default to Black. This changes the background colour of the Navigation and Status bars to black, and their text to white. So the battery and other icons and text in the status bar will look white when the app is running.
In the same Navigation Bar group, change the Bar Tint to the colour of your liking.
If you have Bar Button items in your Navigation Bar, those will still show their text in the default blue colour, so in the Attributes Inspector, View group, change the Tint to White Colour.
That should get you what you want. Here is a screenshot that would make it easier to see where to make the changes.

Bar Tint: Background color of navigation bar
Title Color/Large Title color: color of title text in navigation bar
Tint: color of left and right button text in navigation bar

Source: https://stackoverflow.com/questions/18929864/how-to-change-navigation-bar-color-in-ios-7