iOS__更改选择图片控制器的NavitionBarItem字体颜色

• (void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated
  {
  viewController.navigationItem.rightBarButtonItem.tintColor = [UIColor blackColor];
  viewController.navigationItem.leftBarButtonItem.tintColor = [UIColor blackColor];
  }