swift - 使用键盘按顺序定位文本字段。 swift 4.2，Xcode 10

Question

假设当前 View Controller 中有 4 个文本框、1 个选择器和 1 个按钮。我在键盘上添加了两个额外的按钮，如下所示:

(按钮图像不是那么重要)我正在尝试的是:假设我单击第二个文本字段。然后应用程序向我显示带有这些按钮的键盘。我想用这些按钮切换文本字段。第一个按钮专注于上一个(第一个文本字段)第二个按钮专注于下一个(第三个文本字段)。它应该像这样循环进行。

循环意味着:假设用户点击了第 4 个文本字段。然后让我们假设用户键盘上的下一步按钮。所以应用程序必须专注于第一个文本字段。

这是源代码:

导入 UIKit类 TestViewController: UIViewController, UITextFieldDelegate {

@IBOutlet weak var textField1Outlet: UITextField!
@IBOutlet weak var textField2Outlet: UITextField!
@IBOutlet weak var textField3Outlet: UITextField!
@IBOutlet weak var textField4Outlet: UITextField!
@IBOutlet var contentViewOutlet: UIView!

override func viewDidLoad() {
    super.viewDidLoad()

    self.textField1Outlet.delegate = self
    self.textField2Outlet.delegate = self
    self.textField3Outlet.delegate = self
    self.textField4Outlet.delegate = self

    let toolBar = UIToolbar()
    toolBar.sizeToFit()

    let lastItemButton = UIBarButtonItem(barButtonSystemItem: UIBarButtonItem.SystemItem.rewind, target: self, action: #selector(self.switchToTheLastTextfield))
    let nextItemButton = UIBarButtonItem(barButtonSystemItem: UIBarButtonItem.SystemItem.fastForward, target: self, action: #selector(self.switchToTheNextTextfield))

    toolBar.setItems([lastItemButton, nextItemButton], animated: false)

    textField1Outlet.inputAccessoryView = UIView()
    textField2Outlet.inputAccessoryView = UIView()
    textField3Outlet.inputAccessoryView = UIView()
    textField4Outlet.inputAccessoryView = UIView()

    textField1Outlet.inputAccessoryView = toolBar
    textField2Outlet.inputAccessoryView = toolBar
    textField3Outlet.inputAccessoryView = toolBar
    textField4Outlet.inputAccessoryView = toolBar

}

@objc func switchToTheLastTextfield(_ textField: UITextField)
{
    **// help for this scope please**
}

@objc func switchToTheNextTextfield(_ textField: UITextField)
{
    **// help for this scope please**
}

}

我需要编写这两个方法:switchToTheLastTextfield 和switchToTheNextTextfield。也许一种方法足以管理聚焦下一个和上一个文本字段。

我尝试使用下面的方法实现这些功能，但效果不佳。我试过这个方法:

@objc func switchToTheNextTextfield()
{
    guard let contentView = self.contentViewOutlet else
    {
        return
    }
    for view in contentView.subviews
    {
        if let tField = view as? UITextField
        {
            if (tField == textField1Outlet)
            {
                textField2Outlet.becomeFirstResponder()
            }
            else if (tField == textField2Outlet)
            {
                textField3Outlet.becomeFirstResponder()
            }
            else if (tField == textField3Outlet)
            {
                textField4Outlet.becomeFirstResponder()
            }
            else if (tField == textField4Outlet)
            {
                textField1Outlet.becomeFirstResponder()
            }
        }
    }
}

( swift 4.2，Xcode 10)顺便说一句，这是一个细节:如果下一项不是文本字段应用程序不应该崩溃。这个场景也应该管理。

Answer 1

此处的主要思想是拥有一个包含所有文本字段的数组，以便更清楚地分配急救人员。设置完成后，只需设置您的辅助函数 switchToTheNextTextfield 和 switchToTheLastTextfield。在这些函数中，只需遍历文本字段并查看哪个是当前的第一响应者，然后使数组中的下一个/上一个文本字段成为第一响应者。查看示例代码和注释。

@IBOutlet weak var textField1Outlet: UITextField!
@IBOutlet weak var textField2Outlet: UITextField!
@IBOutlet weak var textField3Outlet: UITextField!
@IBOutlet weak var textField4Outlet: UITextField!
// have a variable which is an array of the textFields to make it easy to cycle around without a long if condition
lazy var textFields: [UITextField] = [textField1Outlet, textField2Outlet, textField3Outlet, textField4Outlet]
@IBOutlet var contentViewOutlet: UIView!

override func viewDidLoad() {
  super.viewDidLoad()

  // 1. These can be replaced with below
  /*
  self.textField1Outlet.delegate = self
  self.textField2Outlet.delegate = self
  self.textField3Outlet.delegate = self
  self.textField4Outlet.delegate = self
 */

  // 1. These can replace assigning each of the textFields delegate
  textFields.forEach { textField in
    textField.delegate = self
  }

  let toolBar = UIToolbar()
  toolBar.sizeToFit()

  let lastItemButton = UIBarButtonItem(barButtonSystemItem: UIBarButtonItem.SystemItem.rewind, target: self, action: #selector(self.switchToTheLastTextfield))
  let nextItemButton = UIBarButtonItem(barButtonSystemItem: UIBarButtonItem.SystemItem.fastForward, target: self, action: #selector(self.switchToTheNextTextfield))

  toolBar.setItems([lastItemButton, nextItemButton], animated: false)

  // Don't need these since you'll immediate assign toolBar to the textFields
  /*
  textField1Outlet.inputAccessoryView = UIView()
  textField2Outlet.inputAccessoryView = UIView()
  textField3Outlet.inputAccessoryView = UIView()
  textField4Outlet.inputAccessoryView = UIView()
  */

  // These can also be replaced with the code below
  /*
  textField1Outlet.inputAccessoryView = toolBar
  textField2Outlet.inputAccessoryView = toolBar
  textField3Outlet.inputAccessoryView = toolBar
  textField4Outlet.inputAccessoryView = toolBar
 */

  textFields.forEach { textField in
    textField.inputAccessoryView = toolBar
  }

}

@objc func switchToTheLastTextfield(_ textField: UITextField)
{
  guard let contentView = self.contentViewOutlet else
  {
    return
  }

  for (index, textField) in textFields.enumerated() {
    if textField.isFirstResponder {
      var previousIndex = index == 0 ? textFields.count - 1 : index - 1  // ternary to determine the previous index
      textFields[previousIndex].becomeFirstResponder()
      return
    }
  }
}

@objc func switchToTheNextTextfield()
{
  guard let contentView = self.contentViewOutlet else
  {
    return
  }

  for (index, textField) in textFields.enumerated() {
    if textField.isFirstResponder {
      var nextIndex = index == textFields.count - 1 ? 0 : index + 1   // ternary to determine the next index
      textFields[nextIndex].becomeFirstResponder()
      return
    }
  }
}