Question

我使用导航控制器和模态显示segues。如果[条件]不成立，我想阻止第二个视图控制器的后退按钮，例如，当用户按下后退按钮时，添加警告“你不能回到[条件]”。

如果有人知道如何解决它，不知道是否可能！

Thanksss

Answer 1

您需要为后栏按钮项添加自定义操作。

@IBAction func backPressed(_ sender: UIBarButtonItem) {
     if !myCondition {
          let alert = UIAlertViewController(title: "Alert", message: "Please fulfill the condition")
          let action = UIAlertAction(title: "OK", .default)
          self.present(alert, animated: true)
          return
     }
     navigationController?.popViewController(animated: true)
}

或者您可以使用代码中的常规目标操作。

myBarButton.addTarget(self, selector: #selector(backButtonPressed(_:)))

抱歉语法不正确。

Answer 2

需要后退按钮图片“ic-menu-back-primary”

override func viewDidLoad() {
    super.viewDidLoad()

    // Nav Back Button
    self.navigationItem.hidesBackButton = true
    let backButton = UIBarButtonItem(image: #imageLiteral(resourceName: "ic-menu-back-primary"), style: .plain, target: self, action: #selector(back(_:)))
    navigationItem.leftBarButtonItem = backButton
}


@IBAction func back(_ sender: Any?) {

    let alert = UIAlertController(title: nil, message: "You can't go back until [condition]", preferredStyle: .alert)

    let resume = UIAlertAction(title: "Cancel", style: .cancel)
    let cancel = UIAlertAction(title: "Exit", style: .default) { (action) in
        self.navigationController?.popViewController(animated: true)
    }

    alert.addAction(resume)
    alert.addAction(cancel)

    present(alert, animated: true)
}

为模态推送segue添加条件

2 个答案: