使用 uipickerView 时将 OF 对象保存到数组中

Question

我对 Swift 比较陌生。我在 pickerView 中使用 PFQuery 时遇到了问题。

我正在尝试实现一个 2 组件的 pickerView，如下所示：

组件 0：组件 1

“A”：“Altivo”、“Altrez”

“B”：“贝弗利”、“比茹”

从组件 0 中选择“A”将在组件 1 中显示“Altivo”、“Altrez”

使用来自 Component 0 的值从 Parse 中查询来自 Component 1 的值

这是我的代码：

var condoNameList: [String] = [String]()
var condoPicker = UIPickerView()
var condoAlphabet: [String] = [String]()
private let prefixComponent = 0
private let condoNameComponent = 1


 override func viewDidLoad() {
    super.viewDidLoad()
    condoAlphabet = ["A", "B"]
 }

 //Start: For condoName picker
func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int {
    return 2
}

func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
    if component == prefixComponent{
        return condoAlphabet.count
    }else {
        return self.condoNameList.count

    }
}

func pickerView(pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    if component == prefixComponent {
        condoNameList.removeAll()
        let query = PFQuery(className: "condodirectory")
        let selectedalphabet: String = condoAlphabet[row] as String!

        query.whereKey("condoName", hasPrefix: selectedalphabet)
        query.findObjectsInBackgroundWithBlock{
            (objects:[PFObject]?, error:NSError?)->Void in

            if error == nil{
                for object in objects!{
                    //print(object)
                    let condoName:String = object["condoName"] as! String
                    self.condoNameList.append(condoName)
                }
            }
            //print("condo Name List is \(self.condoNameList)") //Position 1
        }
        print("condo Name List is \(self.condoNameList)") //Position 2
        condoPicker.reloadComponent(condoNameComponent)
        condoPicker.selectRow(0, inComponent: condoNameComponent, animated: true)
    }
}

func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
    if component == prefixComponent{
        return condoAlphabet[row]
    }else {
        return self.condoNameList[row]
    }
}

问题出在位置 1，打印函数能够打印出 condoNameList，但在位置 2，它会打印一个空数组。因此，组件 1 的列表没有显示在 PickerView 中。

有人知道为什么吗？

提前感谢您的帮助。

Answer 1

我设法通过使用 didset{} 方法从另一个线程解决了问题。

var condoNameList: [String] = [] {
        didSet {
            self.condoNameListTemp = condoNameList
            condoName.inputView = condoPicker
            condoPicker.reloadAllComponents()
        }
    }