ios - pickerview 不显示数组中的数据

Question

PikerView 在我的 View Controller 中没有显示数据。

当我用一些数组文字值测试它时，它工作正常。

我应该在某处重新加载数据吗？

class FirstViewController: UIViewController, UIPickerViewDelegate, UIPickerViewDataSource
{
    @IBOutlet var baseCurrency: UITextField!
    @IBOutlet var excahngeCurrency: UITextField!
    @IBOutlet var dropDown: UIPickerView!

    var list: [String: AnyObject] = [String: AnyObject]()
    var titles: [String] = []
    override func viewDidLoad()
    {
        super.viewDidLoad()

        let url:URL = URL(string: "https://openexchangerates.org/api/currencies.json?app_id=7486951aeb994599a08cd7979bef3c03")!
    Alamofire.request(url).responseJSON(completionHandler:
        {
            response in
            switch response.result
            {
            case.success:
                self.list = response.result.value as! [String: AnyObject]
                for (key, _) in self.list
                {
                    self.titles += [key]
                }

                print(self.titles)
            case.failure:
                print("error")
            }
        })
    }

    func numberOfComponents(in pickerView: UIPickerView) -> Int
    {
        return 1
    }

    func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String?
    {
        return self.titles[row]
    }

    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int
    {
        return self.titles.count
    }

    func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int)
    {
        exchangeCurrency.text = self.titles[row]
    }
}

Answer 1

假设您确实从 URL 获取数据(我没有验证这一点，我假设您确实在您的 print 语句中看到了数据)您需要调用 reloadAllComponents 在您的 pickerview 上，以便它在获取数据后重新加载数据。