方法是让当前控制器取代导航的手势代理，控制器消失时再还回去，略麻烦但无副作用
// 设置属性保存导航的interactivePopGestureRecognizer的代理，记得使用weak标记弱引用
weak var savedGestureRecognizerDelegate:UIGestureRecognizerDelegate?
// 在进入控制器时保存导航的interactivePopGestureRecognizer属性
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
savedGestureRecognizerDelegate = self.navigationController?.interactivePopGestureRecognizer?.delegate
self.navigationController?.interactivePopGestureRecognizer?.delegate = self
}
//离开控制器的时候，把导航的delegate还回去
override func viewWillDisappear(_ animated: Bool) {
self.navigationController?.interactivePopGestureRecognizer?.delegate = savedGestureRecognizerDelegate
}
//遵守UIGestureRecognizerDelegate协议，把手势返回的代理方法实现为空
func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
if gestureRecognizer == self.navigationController?.interactivePopGestureRecognizer {
return false
}
return true
}
