从 UIPickerView 接收输入时如何更新 UITextField？

Question

目前，我正在以编程方式在cellForRowAt 中创建UITextField 和UIPickerView。如果我将UITextField 连接到IBOutlet，我可以轻松更新didSelectRow 中选定的UIPickerView 值。

但是，我需要以编程方式创建 UITextField，并应用 AutoLayout 约束。

但是，我不知道如何更新 UITextField，因为我在 UIPickerView's didSelectRow 函数中没有引用它，因为它是在 cellForRowAt 中以编程方式创建的，如下所示：

var testing: [String] = []

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell
{
    // Dequeue the cell to load data
    let cell: UITableViewCell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)

    if indexPath.section == 2
    {
        let wearsPickerView: UIPickerView = UIPickerView()

        wearsPickerView.delegate = self
        wearsPickerView.dataSource = self

        let textField: UITextField = UITextField()

        textField.translatesAutoresizingMaskIntoConstraints = false

        textField.textColor = UIColor.black

        textField.text = "Test"

        textField.delegate = self
        textField.inputView = wearsPickerView

        cell.contentView.addSubview(textField)

        let leadingConstraint = NSLayoutConstraint(item: cell.contentView, attribute: NSLayoutAttribute.leading, relatedBy: NSLayoutRelation.equal, toItem: textField, attribute: NSLayoutAttribute.leading, multiplier: 1.0, constant: 0)
        let trailingConstraint = NSLayoutConstraint(item: cell.contentView, attribute: NSLayoutAttribute.trailing, relatedBy: NSLayoutRelation.equal, toItem: textField, attribute: NSLayoutAttribute.trailing, multiplier: 1.0, constant: 0)
        cell.contentView.addConstraint(leadingConstraint)
        cell.contentView.addConstraint(trailingConstraint)

        let topConstraint = NSLayoutConstraint(item: cell.contentView, attribute: NSLayoutAttribute.top, relatedBy: NSLayoutRelation.equal, toItem: textField, attribute: NSLayoutAttribute.top, multiplier: 1.0, constant: 0)
        let bottomConstraint = NSLayoutConstraint(item: cell.contentView, attribute: NSLayoutAttribute.bottom, relatedBy: NSLayoutRelation.equal, toItem: textField, attribute: NSLayoutAttribute.bottom, multiplier: 1.0, constant: 0)
        cell.contentView.addConstraint(topConstraint)
        cell.contentView.addConstraint(bottomConstraint)
    }

    return cell
}

func textFieldShouldReturn(_ textField: UITextField) -> Bool
{
    textField.resignFirstResponder()

    return true
}

func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int
{
    return testing.count
}

func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String?
{
    return testing[row]
}

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int)
{
    // How to update UITextField string?

}

Answer 1

您可以获取相应索引路径的单元格，并在该单元格中找到文本字段。您有 2 个选项可用于查找 textField。一种是使用标签，以防您在该单元格中有多个UITextFields，而您没有。所以你可以这样做：

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int)
  {
    // choose the correct row. I've assumed you only have one row.
    if let cell = tableView.cellForRow(at: IndexPath(row: 0, section: 2)) {
      for subview in cell.subviews {
        if let textField = subview as? UITextField {
          textField.text = testing[row]
          break
        }
      }
    }
  }