backBarbuttonitem什么都不做？

Question

我已经设置导航程序

在视图控制器我设置了一个后退按钮，只改变标题按照文档。但是，点击子控制器中的后退按钮不会执行任何操作。

我错过了什么？

> in a viewController 

    let backItem = UIBarButtonItem() 
    backItem.title = "" 
    navigationItem.backBarButtonItem = backItem 
    self.navigationController?.pushViewController(secondViewController, animated: true) 

Answer 1

你有一个目标和动作添加到该按钮，

let backItem = UIBarButtonItem() 
backItem.title = "" 
backItem.target = self 
backItem.action = #selector(back) 
navigationItem.backBarButtonItem = backItem 
self.navigationController?.pushViewController(secondViewController, animated: true) 

，然后实现回（）函数。

func back() { 
    // If your view controller was presented by a navigation controller 
    self.navigationController?.popViewControllerAnimated(true) 

    // If your view controller was presented modally 
    self.presentingViewController?.dismiss(animated: true, completion: nil) 
}