4 实现:多次push操作

通过重写UINavigationController push方法 实现多次push

import UIKit

class LYNavigationVc: UINavigationController {

    override func viewDidLoad() {
        super.viewDidLoad()

          //设置返回边缘手势代理
        self.interactivePopGestureRecognizer?.delegate = self
        

    }
    
    
    //重写push方法
    override func pushViewController(_ viewController: UIViewController, animated: Bool) {
        
        //导航控制器属性 多个子控件
        print(viewControllers.count)
        //只有一个
        
        super.pushViewController(viewController, animated: animated)
        
        //调用super super之后 才会将子视图添加到导航控制器
        print(viewControllers.count)
        //两个或者多个
        
        if viewControllers.count > 1 {
            
            if viewControllers.count == 2 {
                //获取第一个导航栏里 子视图控制器的标题
                let title = viewControllers[0].title!
                viewController.navigationItem.leftBarButtonItem = UIBarButtonItem(title: title, imageName: "navigationbar_back_withtext", target: self, action: #selector(popAction))
                
            }else{
                //统一改为返回标题
                viewController.navigationItem.leftBarButtonItem = UIBarButtonItem(title: "返回", imageName: "navigationbar_back_withtext", target: self, action: #selector(popAction))
            }
            
            viewController.title = "当前显示的是第\(viewControllers.count)级控制器"
        }
        
        
    }
    

/*    bug:
    界面跳转:阴影
            window设置为白色
            tabbar设置背景图片
 */

    @objc private func popAction() {
        self.popViewController(animated: true)
    }


extension LYNavigationVc : UIGestureRecognizerDelegate {
    
    //是否处理点击的边缘手势
    func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
        
        //根控制器 不处理边缘手势
        if viewControllers.count == 1{
            
            return false
        }
        return true
    }
}