Add custom back button on navigation controller in iOS 7

if ([[[UIDevice currentDevice] systemVersion] intValue]>=7) {   

        NSLog(@"iOS 7 back button");

        

        UIButton *backButton = [[UIButton alloc] initWithFrame: CGRectMake(0, 0, 44.0f, 30.0f)];

        [backButton setImage:[UIImage imageNamed:@"CustomBack.png"]forState:UIControlStateNormal];

        [backButton addTarget:self action:@selector(popVC) 

                forControlEvents:UIControlEventTouchUpInside];

        self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] 

                initWithCustomView:backButton];        

    } else{

        NSLog(@"Do nothing for iOS 6 back button");

    }

- (void) popVC { // Pop action of custom back button

    [self.navigationController popViewControllerAnimated:YES];

}