Question

如果文本框值等于nil，我想取消展开segue。下面是当前的代码。我使用故事板连接保存按钮（将文本值保存到数据库中）。我正在考虑使用poptorootviewcontroller来确保教科书在执行segue之前具有值。他们用现有的代码做任何方式吗？

mainView中的代码放松回来 -

@IBAction func unwind(_ segue: UIStoryboardSegue){
    print("Back in TableView")

}

childView上的

按钮执行展开segue -

 @IBAction func saveAddress(_ sender: UIButton) {
    // save values to dictionary save dictionary to firebase under user, uid, addresses
    // uialert controller if fields are not completed do not allow segue if fields are not complete
    // perform segue to addresstableview

    let addy1: String = address1Txt.text!
    let addy2: String = address2Txt.text!
    let aptNum: String = aptTxt.text!
    let city: String = cityTxt.text!
    let state: String = stateTxt.text!
    let zip: String = zipTxt.text!

    // add UIAlert controller for address field == nothing
    if addy1.isEmpty && aptNum.isEmpty && city.isEmpty && state.isEmpty && zip.isEmpty
    {
        //add UIAlert Controller DO NOT PERFORM SEGUE IF TRUE
    }

    Address.sharedInsance.typedNewAddress = addy1 + "," + addy2 + "," + aptNum + "," + city + "," + state + "," + zip

    print("address save print",addy1, addy2, aptNum, city, state, zip)
    let key = ref.child("address").childByAutoId().key
    let setter = false
    let addyDict = ["address line 1":addy1,"address line 2":addy2,"apt Number":aptNum,"city":city,"state":state,"zip":zip,"keyID": key, "setter": setter] as [String : Any]
    let userID = Auth.auth().currentUser?.uid
    let childUpdates = ["/address/\(key)": addyDict]
    ref.child("users").child(userID!).updateChildValues(childUpdates)

}

Answer 1

鉴于我没有看到您在@IBAction中执行segue，我们必须假设您将按钮连接到@IBAction和展开segue。您应该从右侧面板上最后一个选项卡上的按钮“Connections Inspector”中删除segue，而是从视图控制器本身创建一个展开segue到出口：

然后，您可以在左侧面板中选择该segue，单击该segue的“属性检查器”，为其指定一个故事板标识符：

然后，您可以使用该故事板标识符以编程方式执行segue，仅适用于您剩余的@IBAction，例如

@IBAction func didTapDoneButton(_ sender: Any) {
    // if the fields are `nil` or have a length of zero characters, show warning
    // and just `return` without ever performing unwind segue

    guard let firstName = textFieldFirstName.text?.trimmingCharacters(in: .whitespacesAndNewlines),
        let lastName = textFieldLastName.text?.trimmingCharacters(in: .whitespacesAndNewlines),
        firstName.count > 0, lastName.count > 0 else {
            let alert = UIAlertController(title: nil, message: "Please fill in all fields", preferredStyle: .alert)
            alert.addAction(UIAlertAction(title: "OK", style: .default))
            present(alert, animated: true)
            return
    }

    // do something with firstName and lastName

    save(firstName: firstName, lastName: lastName)

    // now perform unwind segue

    performSegue(withIdentifier: "unwindHome", sender: sender)
}

向您展示了这一点后，我认为更强大的方法是不要让用户点击“完成”/“保存”按钮，直到输入所需的字段。底线，而不是处理错误情况，设计一个不可能出现这种错误的UI。

因此，其中一些关键方面包括：

调暗/禁用“完成”/“保存”按钮;
设置文本字段的“占位符文本”以指示该字段是必需的。例如。 “名字（必填）”的占位符，以便用户知道它是必需的。

为各种文本字段添加editingChanged方法，根据需要启用/禁用“完成”按钮：

@IBAction func editingChanged(_ sender: UITextField) {
    if let firstName = textFieldFirstName.text?.trimmingCharacters(in: .whitespacesAndNewlines),
        let lastName = textFieldLastName.text?.trimmingCharacters(in: .whitespacesAndNewlines),
        firstName.count > 0, lastName.count > 0 {
        doneButton.isEnabled = true
    } else {
        doneButton.isEnabled = false
    }
}

显然可以将其与所有相关文本字段的“editingChanged”操作联系起来。

这会产生一个“完成”按钮（本演示文稿右上角的按钮），在所有文本字段中至少有一些文本被禁用：

底线，而不是处理错误，首先阻止它。

Answer 2

您应该覆盖shouldPerformSegue方法，如果教科书字段为空，则返回false。

override func shouldPerformSegue(withIdentifier identifier: String, sender: Any?) -> Bool {

}

展开segue取消文本框值等于nil

2 个答案: