Swift 中的 UIPickerView

Question

我有一个标签，我想以编程方式从我的用户那里添加生日，我设法用数据填充，但我无法正确提取数据，这是我的代码：显示错误，例如索引超出范围，然后崩溃我的应用程序

class SignUpFormViewController: UIViewController {

    let date = Date()
    let formatter = DateFormatter()
    let years = (1800...2100).map{String($0)}
    let days = (1...31).map{String($0)}
    var pickerMonth: [String] = [String]()
    var pickerDay: [String] = [String]()
    var pickYears: [String] = [String]()

    var selectedMonth: String?
    var selectedDay: String?
    var selectedYear: String?

//other stuff

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        handleGestureRecognizer()
        self.datePickerView.delegate = self
        self.datePickerView.dataSource = self
        datePickerComponents()
    }

}

extension SignUpFormViewController: UIPickerViewDelegate, UIPickerViewDataSource {

    func numberOfComponents(in pickerView: UIPickerView) -> Int {
        return 3
    }

    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {

        if component == 0 {
            return pickerMonth.count//month
        }else if component == 1 {
            return pickerDay.count//day
        }else {
            return pickYears.count//year
        }
    }

    func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {

        if component == 0 {
            return pickerMonth[row]
        }else if component == 1 {
            return pickerDay[row]
        }else {
            return pickYears[row]
        }
    }

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

        birthDateTextField.text = "\(pickerMonth[row])/\(pickerDay[row])/\(pickYears[row])"
    }

    func datePickerComponents() {
        pickerMonth = formatter.shortMonthSymbols
        pickerDay = days
        pickYears = years
    }

}

Answer 1

问题在这里：

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    birthDateTextField.text = "\(pickerMonth[row])/\(pickerDay[row])/\(pickYears[row])"
}

太单纯了。 想想看。 用户一次只旋转一个组件，然后调用您的方法。 假设它是用户旋转的年份组件。 你有300个。 所以row可能是 300（比方说）。 但是pickerMonth中没有300 个月！ 因此，当您天真地说出pickerMonth[row]时，您会崩溃。

您想要做的是询问选择器视图在所有三个组件中选择了哪一行，并将该行用于该组件。

birthDateTextField.text = 
    pickerMonth[pickerView.selectedRow(inComponent:0)]
    + "/" + 
    pickerDay[pickerView.selectedRow(inComponent:1)]
    + "/" + 
    pickYears[pickerView.selectedRow(inComponent:2)]