我们有时候在开发iOS的时候，涉及到跳转界面时，需要隐藏tabbar，以便我们重新定义新的。

OC版本的：

//1.设置self.tabBarController.tabBar.hidden=YES;

self.tabBarController.tabBar.hidden=YES;

//2.如果在push跳转时需要隐藏tabBar，设置self.hidesBottomBarWhenPushed=YES;

self.hidesBottomBarWhenPushed=YES;
NextViewController *next=[[NextViewController alloc]init];
[self.navigationController pushViewController:next animated:YES];
self.hidesBottomBarWhenPushed=NO;

//注意：在push后设置self.hidesBottomBarWhenPushed=NO;

其实在OC中直接对next.hidesBottomBarWhenPushed=YES就可以在跳转界面的时候隐藏tabbar

而不需要设置self.hidesBottomBarWhenPushed=NO;

Swift版本的：

let  testVC = UIViewController()
self.hidesBottomBarWhenPushed = true
self.navigationController?.pushViewController(testVC,animated: true)
self.hidesBottomBarWhenPushed = false

如果是push到下个界面就没有问题，如果从第二个界面push到第三个界面，再返回第二个界面，tabbar就会显示，这样还是达不到我们想要的结果

下面是我自己对hidesBottomBarWhenPushed 属性设置的一个总结，应该每一次push，都去执行对hidesBottomBarWhenPushed属性进行设置，如

果要push的界面多了，那不是做很多繁琐的工作，所以自定义了UINavigationController，对hidesBottomBarWhenPushed属性进行统一设置

import UIKit

class BaseNavigationController: UINavigationController {

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    
    //每一次push都会执行这个方法，push之前设置viewController的hidesBottomBarWhenPushed
    override func pushViewController(_ viewController: UIViewController,animated: Bool) {
        viewController.hidesBottomBarWhenPushed = true
        super.pushViewController(viewController,animated: true)
        viewController.hidesBottomBarWhenPushed = false
       
    }
    
    override func popViewController(animated: Bool) -> UIViewController? {
        
        //以下函数是对返回上一级界面之前的设置操作
        //每一次对viewController进行push的时候，会把viewController放入一个栈中
        //每一次对viewController进行pop的时候，会把viewController从栈中移除
        if self.childViewControllers.count == 2
        {
            //如果viewController栈中存在的ViewController的个数为两个，再返回上一级界面就是根界面了
            //那么要对tabbar进行显示
            let controller:UIViewController = self.childViewControllers[0]
            controller.hidesBottomBarWhenPushed = false
            
        }
        else
        {
            //如果viewController栈中存在的ViewController的个数超过两个，对要返回到的上一级的界面设置hidesBottomBarWhenPushed = true
            //把tabbar进行隐藏
            let count = self.childViewControllers.count-2
            let controller = self.childViewControllers[count]
            controller.hidesBottomBarWhenPushed = true
        }
        
        
        return super.popViewController(animated: true)
    }

}