自定义默认导航栏外观

// Default UINavigationBar appearance throughout the app
[[UINavigationBar appearance] setTitleTextAttributes:@{NSForegroundColorAttributeName: [UIColor whiteColor],
                                                       NSFontAttributeName : [UIFont fontWithName:@"HelveticaNeue-CondensedBold" size:17],
                                                       }];

[[UINavigationBar appearance] setTintColor:[UIColor whiteColor]];
[[UINavigationBar appearance] setBarTintColor:[UIColor KNGRed]];
[[UINavigationBar appearance] setTranslucent:NO];
[[UINavigationBar appearance] setBarStyle:UIBarStyleBlack];
[[UIBarButtonItem appearanceWhenContainedIn: [UISearchBar class], nil] setTintColor:[UIColor KNGGray]];