UINavigationController "Back" button - custom handling

ViewController.m

// Navigation BACK Button - custom
- (void)viewDidLoad {
    [super viewDidLoad];

    UIBarButtonItem *backButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"Backk" style:(UIBarButtonItemStylePlain) target:self action:@selector(back:)];
    self.navigationItem.backBarButtonItem = backButtonItem;
    self.navigationItem.hidesBackButton = NO;
}

- (void)back:(id)button {
    if (self.webView.canGoBack) {
        [self.webView goBack];
    } else {
        [self.navigationController popViewControllerAnimated:YES];
    }
}