IOS7禁用和开启POP手势

- (void)viewDidAppear:(BOOL)animated{
  [super viewDidAppear:animated];
  // 禁用 iOS7 返回手势
  if ([self.navigationController respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
    self.navigationController.interactivePopGestureRecognizer.enabled = NO;
  }
}

- (void)viewWillDisappear:(BOOL)animated{
  [super viewWillDisappear:animated];
  // 开启
  if ([self.navigationController respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
    self.navigationController.interactivePopGestureRecognizer.enabled = YES;
  }
}