繼承了NavigationController，但是Push VC時有時會卡死，但是可以手勢滑動。

解決方案：
@interface ZZBaseNaviController () <UINavigationControllerDelegate>
@end
@implementation ZZBaseNaviController

• (void)viewDidLoad {
  [super viewDidLoad];

  self.delegate = self;
  }

pragma mark - UINavigationControllerDelegate

• (void)navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animated {
  self.interactivePopGestureRecognizer.enabled = [self.viewControllers count] > 1;
  }
  @end