具有多个组件的动态PickerView：索引超出范围

Question

我有一个基于此code的包含3个组件的PickerView。右边的两个选择器根据左边的先前选择更改其内容。不幸的是，当我将父选择器更改为行数少于预览数的另一个选择器时，应用程序崩溃：🛑致命错误：索引超出范围。

我试图在选择另一个父选择器之后将子选择器返回到其第一位置，但是没有成功。 （请参见didSelectRow下的>

您还有其他想法吗？

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

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

    if component == 0 {
        return countries.count
    } else if component == 1 {
        let selectedCountry = pickerView.selectedRow(inComponent: 0)
        return countries[selectedCountry].cities.count
    } else {
        let selectedCountry = pickerView.selectedRow(inComponent: 0)
        let selectedCity = pickerView.selectedRow(inComponent: 1)
        return countries[selectedCountry].cities[selectedCity].posts.count
    }
}

func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
    if component == 0 {
        return countries[row].name
    } else if component == 1{
        let selectedCountry = pickerView.selectedRow(inComponent: 0)
        return countries[selectedCountry].cities[row].name
    } else {
        let selectedCountry = pickerView.selectedRow(inComponent: 0)
        let selectedCity = pickerView.selectedRow(inComponent: 1)
        return countries[selectedCountry].cities[selectedCity].posts[row]
    }
}


func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    pickerView.reloadAllComponents()
    if component == 0 {
        pickerView.selectRow(0, inComponent: 1, animated: true)
        pickerView.selectRow(0, inComponent: 2, animated: true)
    } else if component == 1 {
        pickerView.selectRow(0, inComponent: 2, animated: true)
    }
}

我有一个PickerView，根据此代码包含3个组件。右边的两个选择器根据左边的先前选择更改其内容。不幸的是，当我更改...

Answer 1

当您在reloadAllComponents()中调用didSelectRow时，您尚未更新所选行，因此崩溃了。