Question

当我在选择器视图中选择目标2都工作正常时，下一个视图控制器上的标签文本将更新，一切正常。但是，如果我选择Target 1-打开下一个ViewController时没有任何错误，但标签文本为空nil。

如果您能帮助我或以其他方式进行评估，我将不胜感激。我只是在使用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语句的右花括号。

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)"

第二，我将重新组织代码，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)"
}

无法将数据传递到下一个ViewController取决于UIPickerView textField.text吗？

1 个答案: