我需要执行一个动作(清空一个数组),当UINavigationController的后退按钮被按下,而按钮仍然导致堆栈上的前一个ViewController出现。我如何使用swift来实现这一点?


当前回答

你可以简单地从堆栈中删除不必要的控制器,就像这样:

self.navigationController?.viewControllers.removeAll(where: {
        $0 is FirstViewController || $0 is SecondWithPinController
    })

其他回答

你可以在视图控制器中做一些事情

override func navigationShouldPopOnBackButton() -> Bool {
    self.backAction() //Your action you want to perform.
    return true
}

完整回答使用 当导航条上的“后退”按钮被按下时进行检测

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

    if self.isMovingToParent {

        //your code backView
    }
}

这里有一个最简单的Swift 5解决方案,它不需要你创建一个自定义的后退按钮,也不需要你放弃所有免费获得的UINavigationController左键功能。

正如Brandon A上面建议的那样,你需要在你想要与之交互的视图控制器中实现UINavigationControllerDelegate。一个好方法是创建一个unwind segue,你可以手动或自动地执行,并从自定义完成按钮或后退按钮重用相同的代码。

首先,让你感兴趣的视图控制器(你想检测返回的那个)在它的viewDidLoad中成为导航控制器的委托:

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

其次,在文件底部添加一个扩展,覆盖navigationController(willShow:animated:)

extension PickerTableViewController: UINavigationControllerDelegate {

    func navigationController(_ navigationController: UINavigationController,
                              willShow viewController: UIViewController,
                              animated: Bool) {

        if let _ = viewController as? EditComicBookViewController {

            let selectedItemRow = itemList.firstIndex(of: selectedItemName)
            selectedItemIndex = IndexPath(row: selectedItemRow!, section: 0)

            if let selectedCell = tableView.cellForRow(at: selectedItemIndex) {
                performSegue(withIdentifier: "PickedItem", sender: selectedCell)
            }
        }
    }
}

因为你的问题包含了一个UITableViewController,所以我包含了一种获取用户点击行的索引路径的方法。

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()
        }
    }