I have an app that has a blue tint theme to the entire UI. I also have an embedded search bar in the Navigation Bar on my initial view. My button text color for the app is white and declare that in the app delegate using:
[[UINavigationBar appearance] setTintColor:[UIColor whiteColor]];
[self.navigationController.searchDisplayController.searchBar setTintColor:[UIColor blueColor]];
[searchBar setTintColor:[UIColor blueColor]]
Had the same problem. Solved it by using this code after embedding the search bar into navigation bar.
self.navigationItem.titleView.tintColor = [UIColor blueColor];
Probably not the best solution, but it works.