斯威夫特4.2:

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

    if self.isMovingFromParent {
        // Your code...

    }
}

我的偏好是在导航控制器中覆盖popViewController。这样做的好处是:

你的应用程序保持默认的后退按钮外观和动画，你不需要管理它。如果用户在手机上设置了大号文本，这尤其有用，因为默认的后退按钮会根据用户的设置增加或减少大小。 你可以完全停止视图弹出，不像使用viewWillDisappear。

首先，创建一个自定义导航控制器类(并确保将其分配给故事板中的导航控制器或任何创建导航控制器的地方):

class NavControllerWithBackButtonOverride: UINavigationController {

    var backButtonOverride: (() -> Void)? = nil

    override func popViewController(animated: Bool) -> UIViewController? {

        if backButtonOverride != nil {
            //if anything is assigned to the backButtonOverride the override will run
            self.backButtonOverride!()
            return nil
        } else {
            //otherwise the default popViewController will run
            return super.popViewController(animated: animated)
        }
    }
}

然后通过给backButtonOverride变量赋值，在视图控制器中启用/禁用重载:

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    self.enableCustomBackButton()
}

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

/**
 Custom Back Button
 */

func customBackButtonAction() {
    print("DO THIS INSTEAD")
}

func enableCustomBackButton() {
    if let nav = self.navigationController as? NavControllerWithBackButtonOverride {
        nav.backButtonOverride = { self.customBackButtonAction() }
        nav.interactivePopGestureRecognizer?.isEnabled = false
    }    
}

func disableCustomBackButton() {
    if let nav = self.navigationController as? NavControllerWithBackButtonOverride {
    nav.backButtonOverride = nil
    nav.interactivePopGestureRecognizer?.isEnabled = true
    }
}

注意:我还禁用了interactivePopGestureRecognizer，因为它会导致自定义设置的问题。

一种选择是实现您自己的自定义后退按钮。你需要添加以下代码到你的viewDidLoad方法:

    - (void) viewDidLoad {
        [super viewDidLoad];
        self.navigationItem.hidesBackButton = YES;
        UIBarButtonItem *newBackButton = [[UIBarButtonItem alloc] initWithTitle:@"Back" style:UIBarButtonItemStyleBordered target:self action:@selector(back:)];
        self.navigationItem.leftBarButtonItem = newBackButton;
    }

    - (void) back:(UIBarButtonItem *)sender {
        // Perform your custom actions
        // ...
        // Go back to the previous ViewController
        [self.navigationController popViewControllerAnimated:YES];
    }

更新:

以下是Swift的版本:

        override func viewDidLoad {
            super.viewDidLoad()
            self.navigationItem.hidesBackButton = true
            let newBackButton = UIBarButtonItem(title: "Back", style: UIBarButtonItemStyle.Bordered, target: self, action: "back:")
            self.navigationItem.leftBarButtonItem = newBackButton
        }

       @objc func back(sender: UIBarButtonItem) {
            // Perform your custom actions
            // ...
            // Go back to the previous ViewController
            self.navigationController?.popViewControllerAnimated(true)
        }

更新2:

以下是Swift 3的版本:

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

       @objc func back(sender: UIBarButtonItem) {
            // Perform your custom actions
            // ...
            // Go back to the previous ViewController
            _ = navigationController?.popViewController(animated: true)
        }

在离开电流控制器之前，我需要显示警报。所以我是这样做的:

添加扩展UINavigationController与UINavigationBarDelegate 添加选择器到你的控制器导航

它的工作)

extension UINavigationController: UINavigationBarDelegate {
    public func navigationBar(_ navigationBar: UINavigationBar, shouldPop item: UINavigationItem) -> Bool {
        if let items = navigationBar.items, viewControllers.count < items.count {
            return true
        }

        let clientInfoVC = topViewController as? ClientInfoVC
        if clientInfoVC?.responds(to: #selector(clientInfoVC?.navigationShouldPopOnBack)) ?? false {
            clientInfoVC?.navigationShouldPopOnBack(completion: { isAllowPop in
                if isAllowPop {
                    DispatchQueue.main.async {
                        self.popViewController(animated: true)
                    }
                }
            })
        }

        DispatchQueue.main.async {
            self.popViewController(animated: true)
        }

        return false
    }
}

@objc func navigationShouldPopOnBack(completion: @escaping (Bool) -> ()) {
        let ok = UIAlertAction(title: R.string.alert.actionOk(), style: .default) { _ in
            completion(true)
        }
        let cancel = UIAlertAction(title: R.string.alert.actionCancel(), style: .cancel) { _ in
            completion(false)
        }
        let alertController = UIAlertController(title: "", message: R.string.alert.contractMessage(), preferredStyle: .alert)
        alertController.addAction(ok)
        alertController.addAction(cancel)
        present(alertController, animated: true, completion: nil)
    }

我通过以下方法做到了这一点:

斯威夫特3

override func didMoveToParentViewController(parent: UIViewController?) {
   super.didMoveToParentViewController(parent)

   if parent == nil {
      println("Back Button pressed.")
      delegate?.goingBack()
   }           
}

斯威夫特4

override func didMove(toParent parent: UIViewController?) {
    super.didMove(toParent: parent)

    if parent == nil {
        debugPrint("Back Button pressed.")
    }
}

不需要自定义后退按钮。

override func willMove(toParent parent: UIViewController?)
{
    super.willMove(toParent: parent)
    if parent == nil
    {
        print("This VC is 'will' be popped. i.e. the back button was pressed.")
    }
}