How can I change the text and icon colors for tabBarItems in iOS 7?

There are two things you need to do for this:

1) If you want to customize the TabBar itself, you need to set the barTintColor for the tabBarController:

    // this will generate a black tab bar
    tabBarController.tabBar.barTintColor = [UIColor blackColor];

    // this will give selected icons and text your apps tint color
    tabBarController.tabBar.tintColor = appTintColor;  // appTintColor is a UIColor *

2) Set the tabBarItem text appearance for each state that you want to override:

[[UITabBarItem appearance] setTitleTextAttributes:@{NSFontAttributeName : [UIFont fontWithName:@"HelveticaNeue-Bold" size:10.0f],
                                                    NSForegroundColorAttributeName : appTintColor
                                                    } forState:UIControlStateSelected];


// doing this results in an easier to read unselected state then the default iOS 7 one
[[UITabBarItem appearance] setTitleTextAttributes:@{NSFontAttributeName : [UIFont fontWithName:@"HelveticaNeue-Bold" size:10.0f],
                                                    NSForegroundColorAttributeName : [UIColor colorWithRed:.5 green:.5 blue:.5 alpha:1]
                                                    } forState:UIControlStateNormal];