使用键盘将文本字段聚焦在顺序位置。Swift 4.2，Xcode 10

假设当前视图控制器中有4个文本字段、1个选择器和1个按钮。我在键盘上额外添加了两个按钮，如下所示：

（按钮图像并不那么重要）我尝试的是： 假设我点击了第二个文本字段。然后应用程序向我展示了带有这些按钮的键盘。我想用这些按钮切换文本字段。第一个按钮聚焦于上一个（第一个文本字段）第二个按钮聚焦于下一个（第三个文本字段）。它应该像这样循环下去

循环的意思是：假设用户单击了第四个文本字段。然后让我们假设用户按下键盘上的“下一步”按钮。所以应用程序必须关注第一个文本字段

以下是源代码：

导入UIKit 类TestViewController:UIViewController、UIExtFieldDelegate{

@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**
}

}

我需要编写这两种方法：

switchToTheLastTextfield

和

switchToTheNextTextfield

。也许一种方法就足以管理聚焦的next和previos文本字段

我尝试使用以下方法实现这些功能，但效果不佳。我尝试了以下方法：

@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：如果下一个项目不是textfield，应用程序不应该崩溃。这个场景也应该被管理。

一般来说，我不会“手动”循环浏览你的门店：添加所有相关的（目前为4个）输入到列表中，并使用指示所选变量的额外变量在列表中循环。

尝试以下解决方案：

声明一个

UITextfield

变量，并在

textfielddebeginediting

方法中分配当前活动的textfield

使用按钮操作方法检查活动文本字段，并在其中使用

becomeFirstResponder

逻辑

var currentTextField = UITextField()

func textFieldDidBeginEditing(_ textField: UITextField) {
    self.currentTextField = textField
}

@objc func switchToTheNextTextfield()
{
    switch self.currentTextField {
    case textField1Outlet:
        textField2Outlet.becomeFirstResponder()
    case textField2Outlet:
        textField3Outlet.becomeFirstResponder()
    case textField3Outlet:
        textField4Outlet.becomeFirstResponder()
    case textField4Outlet:
        textField1Outlet.becomeFirstResponder()
    default:
        print("Out of scope")
    }
}

---

这里的主要思想是创建一个包含所有文本字段的数组，以使分配第一响应者更为简洁。设置完成后，只需设置助手函数switchToTheNextTextfield，以及switchToTheLastTextfield。在这些函数中，只需遍历文本字段并查看其中一个是当前的firstresponder，然后使数组中的下一个/上一个文本字段成为firstresponder。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
    }
  }
}

---

使用亲爱的@RajeshKumarR事实上，我不想使用cocoa pod来实现此功能。你能帮我编写解决方案吗？请不要将“一般想法”作为答案，而是使用直接帮助操作员的东西！他们会尝试！