为什么不是根视图控制器时 hidesBottomBarWhenPushed 不起作用？答案

【问题标题】：Why is hidesBottomBarWhenPushed not working when not root view controller?为什么不是根视图控制器时 hidesBottomBarWhenPushed 不起作用？
【发布时间】：2017-04-15 12:45:49
【问题描述】：

一个视图控制器被推送，底部标签栏被隐藏，如下所示：

let myViewController = self.storyboard?.instantiateViewController(withIdentifier: MyViewController) as! MyViewController 
myViewController.hidesBottomBarWhenPushed = true
navigationController?.pushViewController(myViewController, animated: true)

效果很好。

但是，当我在推送之前更改根视图控制器时，底部栏不会隐藏。

// Change the root view controller
let firstRootViewController = UIApplication.shared.keyWindow!.rootViewController
UIApplication.shared.keyWindow!.rootViewController = secondRootViewController

// Push view on stack of navigation controller which is a child of firstRootViewController
let myViewController = self.storyboard?.instantiateViewController(withIdentifier: MyViewController) as! MyViewController 
myViewController.hidesBottomBarWhenPushed = true
navigationController?.pushViewController(myViewController, animated: true)

// Some more things happen...

// Switch back to previous root view controller
UIApplication.shared.keyWindow!.rootViewController = firstRootViewController

结果是导航控制器正确推送了myViewController，但底部栏可见，好像参数hidesBottomBarWhenPushed被忽略了一样。

这里有什么问题？

【问题讨论】：

标签： swift uinavigationcontroller pushviewcontroller

【解决方案1】：

解决方案是不更改根视图控制器，而仅将视图添加到 keyWindow：

// Add another view on top of all views
UIApplication.shared.keyWindow?.addSubView(self.view)

// Push view on stack of navigation controller which is a child of firstRootViewController
let myViewController = self.storyboard?.instantiateViewController(withIdentifier: MyViewController) as! MyViewController 
myViewController.hidesBottomBarWhenPushed = true
navigationController?.pushViewController(myViewController, animated: true)

// Some more things happen...

// Remove topmost view
self.view.removeFromSuperview()

【讨论】：