当返回按钮按下，忽略交互式弹出与屏幕边缘手势。

override func viewWillDisappear(_ animated: Bool) {
    super.viewWillDisappear(animated)
    
    if isMovingFromParent, transitionCoordinator?.isInteractive == false {
      // code here
    }
  }

NO

override func willMove(父控件:UIViewController?) {}

即使你在segue到覆盖这个方法的视图控制器，这个也会被调用。其中，检查parent是否为nil或not不是确保移动回正确的UIViewController的精确方法。为了准确地确定UINavigationController是否正确地导航回呈现当前的UIViewController，你将需要遵守UINavigationControllerDelegate协议。

YES

注意:MyViewController只是你想要检测返回的UIViewController的名称。

1)在你的文件顶部添加UINavigationControllerDelegate。

class MyViewController: UIViewController, UINavigationControllerDelegate {

2)添加一个属性到你的类，它将跟踪你正在segue的UIViewController。

class MyViewController: UIViewController, UINavigationControllerDelegate {

var previousViewController:UIViewController

3)在MyViewController的viewDidLoad方法中为你的UINavigationController分配self作为委托。

override func viewDidLoad() {
    super.viewDidLoad()
    self.navigationController?.delegate = self
}

3)在你segue之前，将之前的UIViewController分配为这个属性。

// In previous UIViewController
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "YourSegueID" {
        if let nextViewController = segue.destination as? MyViewController {
            nextViewController.previousViewController = self
        }
    }
}

4)并遵循UINavigationControllerDelegate的MyViewController中的一个方法

func navigationController(_ navigationController: UINavigationController, willShow viewController: UIViewController, animated: Bool) {
    if viewController == self.previousViewController {
        // You are going back
    }
}

Swift 5+(带警报控制的后退按钮)

override func viewDidLoad() {
        super.viewDidLoad()
        
        self.navigationItem.hidesBackButton = true
        let newBackButton = UIBarButtonItem(title: "<Back", style: UIBarButtonItem.Style.plain, target: self, action: #selector(PGWebViewController.back(sender:)))
        self.navigationItem.leftBarButtonItem = newBackButton
}


@objc func back(sender: UIBarButtonItem) {
    
    let alert = UIAlertController(title: "Warning!", message: "Your payment process is not completed yet. Do you want to go back?", preferredStyle: .alert)
        
         let ok = UIAlertAction(title: "OK", style: .default, handler: { action in
             _ = self.navigationController?.popViewController(animated: true)
         })
         alert.addAction(ok)
         let cancel = UIAlertAction(title: "Cancel", style: .default, handler: { action in
         })
         alert.addAction(cancel)
         DispatchQueue.main.async(execute: {
            self.present(alert, animated: true)
    })}

这并不像我们想象的那么难。只需要为UIButton创建一个背景颜色清晰的框架，为按钮分配动作，并放置在导航栏后退按钮上。最后在使用后取下按钮。

这是Swift 3 用UIImage代替UIButton的示例代码

override func viewDidLoad() {
    super.viewDidLoad()
    let imageView = UIImageView()
    imageView.backgroundColor = UIColor.clear
    imageView.frame = CGRect(x:0,y:0,width:2*(self.navigationController?.navigationBar.bounds.height)!,height:(self.navigationController?.navigationBar.bounds.height)!)
    let tapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(back(sender:)))
    imageView.isUserInteractionEnabled = true
    imageView.addGestureRecognizer(tapGestureRecognizer)
    imageView.tag = 1
    self.navigationController?.navigationBar.addSubview(imageView)
    }

编写需要执行的代码

func back(sender: UIBarButtonItem) {

    // Perform your custom actions}
    _ = self.navigationController?.popViewController(animated: true)

    }

执行操作后删除子视图

override func viewWillDisappear(_ animated: Bool) {
    super.viewWillDisappear(animated)

    for view in (self.navigationController?.navigationBar.subviews)!{
        if view.tag == 1 {
            view.removeFromSuperview()
        }
    }

在Swift 5和Xcode 10.2中

请不要添加自定义栏按钮项，使用默认行为。

不需要viewWillDisappear，不需要自定义BarButtonItem等…

最好是检测VC何时从其父对象中移除。

使用这两个函数中的任意一个

override func willMove(toParent parent: UIViewController?) {
    super.willMove(toParent: parent)
    if parent == nil {
        callStatusDelegate?.backButtonClicked()//Here write your code
    }
}

override func didMove(toParent parent: UIViewController?) {
    super.didMove(toParent: parent)
    if parent == nil {
        callStatusDelegate?.backButtonClicked()//Here write your code
    }
}

如果你想停止返回按钮的默认行为，然后添加自定义BarButtonItem。

这就是我的解

extension UINavigationController: UINavigationBarDelegate {
    public func navigationBar(_ navigationBar: UINavigationBar, shouldPop item: UINavigationItem) -> Bool {
        if let shouldBlock = self.topViewController?.shouldPopFromNavigation() {
            return shouldBlock
        }
        return true
    }
}

extension UIViewController {
    @objc func shouldPopFromNavigation() -> Bool {
        return true
    }
}

在你的视图控制器中，你可以这样处理:

@objc override func shouldPopFromNavigation() -> Bool {
        // Your dialog, example UIAlertViewController or whatever you want
        return false
    }