AppDelegate

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    // Overide Back button everywhere.
    UIImage *backButtonImage = [[UIImage imageNamed:@"backButton"]resizableImageWithCapInsets:UIEdgeInsetsMake(0, 15, 0, 3)];
    [[UIBarButtonItem appearance] setBackButtonBackgroundImage:backButtonImage forState:UIControlStateNormal barMetrics:UIBarMetricsDefault];
    
    return YES;
}