Question

我有一个UILabel当前显示“ 0000”和一个带有4个组件的pickerView。每个组件将代表标签中4个字符之一。因此，组件1将更新第一个“ 0”，第二个组件将更新第二个“ 0” ...，依此类推。我已经设法通过简单地按如下所示更新字符串来使用obj-c正确更改它们：

value = [[NSString alloc] initWithFormat:@"0%@%@%@",

但是谈到Swift时，我陷入了困境。我可以从字符串中获取字符，但不能更新标签。到目前为止，这是我的代码：

@IBOutlet weak var matchresult: mylabel!

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {


      var value:String = "0000"

      var firstSelection:Int
      var secondSelction:Int
      var thirdSection:Int
      var forthSelection:Int

      firstSelection = pickerView.selectedRow(inComponent:0)
      secondSelction = pickerView.selectedRow(inComponent:1)
      thirdSection = pickerView.selectedRow(inComponent:2)
      forthSelection = pickerView.selectedRow(inComponent:3)


      //First row selected of first component in pickerview
        if  firstSelection == 0 {

       //Get first character in String 'value'
          if var char = value.character(at: 0) {

          print("I found \(char)")

        //Change the 1st character to 0
          char = "0"

          print("I changed after\(char)")

         //update only the first character in string 'value' with 0
         // ???
         mylabel.text = value         
          }


      //Second row selected of first component in pickerview
        } else if  (firstSelection == 1) {

      //Get first character in String 'value'
          if var char = value.character(at: 0) {

          print("I found \(char)")
      //Change the 1st character to 1
          char = "1"

          print("I changed after\(char)")

      //update only the first character in string 'value' with 1
     // ???

   mylabel.text = value

          }

      }

任何帮助都会很棒。

谢谢

Answer 1

简单的解决方案：

而不是字符串，而是声明一个数组，其中包含选择器视图的4个选定值

var selectedValues = ["0", "0", "0", "0"]

并假设这是数据源

let numbers = ["0", "1", "2", "3", "4", "5", "6", "7", "8", "9"]

func numberOfComponents(in pickerView: UIPickerView) -> Int {
    return 4
}

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

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

在didSelectRow中

更新索引处的值，将数组连接到字符串并显示它

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    selectedValues[component] = numbers[row]
    matchresult.text = selectedValues.joined()
}

如何在Swift中使用标签和pickerview更改和更新String中的某个字符

1 个答案: