ios - 无法将数据传递给下一个ViewController依赖于UIPickerView textField.text？

Question

当我在选择器 View 中选择目标 2 时一切正常，下一个 View Controller 上的标签文本正在更新，一切正常。但是，如果我选择目标 1 - 打开下一个 ViewController，没有任何错误，但标签文本为空 nil。

如果您帮助我或提出其他建议，我将不胜感激。我只是使用 if else 语句来检查 textField。

   override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    let resultsVC = segue.destination as! ResultsViewController

        var declinationDegr = Int()
        if (bodyTextField.text?.contains("Target 1"))! {
            declinationDegr = declinationDegreeTarget1
        } else if (bodyTextField.text?.contains("Target 2"))! {
            declinationDegr = declinationDegreeTarget2
        }
        var declinationMinutes = Double()
        if (bodyTextField.text?.contains("Target 1"))! {
            declinationMinutes = declinationMinutesTarget1
        } else if (bodyTextField.text?.contains("Target 2"))! {
            declinationMinutes = declinationMinutesTarget2
        }
        var declinationDir = String()
        if (bodyTextField.text?.contains("Target 1"))! {
            declinationDir = declinationDirTarget1
        } else if (bodyTextField.text?.contains("Target 2"))! {
            declinationDir = declinationDirTarget2

resultsVC.bdeclString = "\(declinationDegr)º\(String(format: "%.1f", declinationMinutes))'\(declinationDir)"
  }

Answer 1

首先，我认为您缺少最后一个 if/else 语句的右大括号。

var declinationDir = String()
if (bodyTextField.text?.contains("Target 1"))! {
    declinationDir = declinationDirTarget1
} else if (bodyTextField.text?.contains("Target 2"))! {
    declinationDir = declinationDirTarget2
} // CLOSING BRACE MISSING 

resultsVC.bdeclString = "\(declinationDegr)º\(String(format: "%.1f", declinationMinutes))'\(declinationDir)"

其次，我会稍微重新组织一下代码，以避免不必要的字符串比较和强制展开:

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    guard let resultsVC = segue.destination as? ResultsViewController  else {
        // error handling and
        return
    }
    guard let targetText = bodyTextField.text else {
        // error handling and
        return
    }

    var declinationDegr = Int()
    var declinationMinutes = Double()
    var declinationDir = String()

    if (targetText.contains("Target 1")) {
        declinationDegr = declinationDegreeTarget1
        declinationMinutes = declinationMinutesTarget1
        declinationDir = declinationDirTarget1
    } else if (targetText.contains("Target 2")) {
        declinationDegr = declinationDegreeTarget2
        declinationMinutes = declinationMinutesTarget2
        declinationDir = declinationDirTarget2
    } else {
        // error handling
    }

    resultsVC.bdeclString = "\(declinationDegr)º\(String(format: "%.1f", declinationMinutes))'\(declinationDir)"
}