ios - 错误 : Optional(Alamofire. AFError.invalidURL (""))

Question

我刚开始用 Swift 编写代码，在使用 Alamofire 构建应用程序时遇到了这个错误

错误是:

Error: Optional(Alamofire.AFError.invalidURL(""))

这是我的代码。有人可以帮忙吗？？

import UIKit
import Alamofire
import SwiftyJSON


class ViewController: UIViewController, UIPickerViewDataSource, UIPickerViewDelegate {


    let baseURL = "https://apiv2.bitcoinaverage.com/indices/global/ticker/BTC"

    let currencyArray = ["AUD", "BRL","CAD","CNY","EUR","GBP","HKD","IDR","ILS","INR","JPY","MXN","NOK","NZD","PLN","RON","RUB","SEK","SGD","USD","ZAR"]

    let currencySymbolsArray = ["$", "R$", "$", "¥", "€", "£", "$", "Rp", "₪", "₹", "¥", "$", "kr", "$", "zł", "lei", "₽", "kr", "$", "$", "R"]

    var currencySymbol = ""

    var finalURL = ""


    //Pre-setup IBOutlets
    @IBOutlet weak var bitcoinPriceLabel: UILabel!
    @IBOutlet weak var currencyPicker: UIPickerView!

    // determine number of columns
    func numberOfComponents(in pickerView: UIPickerView) -> Int {
        return 1
    }
    // determine number of rows
    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
        return currencyArray.count
    }

    // fill in each row with title from array
    func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
        return currencyArray[row]
    }

    // Print something when you select a row
    func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
        print (currencyArray[row])

        finalURL = baseURL + currencyArray[row]
        print(finalURL)
        currencySymbol = currencyArray[row]
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        currencyPicker.delegate = self
        currencyPicker.dataSource = self

        getCurrencyData(url: finalURL)
    }


    //TODO: Place your 3 UIPickerView delegate methods here

//    //MARK: - Networking
//    /***************************************************************/
    func getCurrencyData(url: String) {
        Alamofire.request(url, method: .get)
            .responseJSON { response in
                if response.result.isSuccess {
                    print("Success! Got the currency data ")

                    let currencyJSON : JSON = JSON(response.result.value!)

                    self.updateCurrencyData(json: currencyJSON)
                } else {
                    print("Error: \(String(describing: response.result.error))")
                    self.bitcoinPriceLabel.text = "Connection issues"
                } 
            }
    }


//    //MARK: - JSON Parsing
//    /***************************************************************/

    func updateCurrencyData(json : JSON) {
        if let currencyResult = json["ask"].double  {
            bitcoinPriceLabel.text = " \(currencySymbol) +  \(currencyResult) "
        } else {
            bitcoinPriceLabel.text = "Currency unavailable"
        }
    }
}

Answer 1

问题是您正在调用 getCurrencyData从您的 View Controller viewDidLoad方法，而 finalURL 的值仍然是它的初始值，即"" ，这正是您在错误消息中看到的无效 URL。

您只需在用户实际使用选择器进行选择后进行网络调用。

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    currencySymbol = currencySymbolsArray[row]
    getCurrencyData(url: baseURL + currencyArray[row])
}

也不需要 finalURL变量，因为您可以直接输入存储在 finalURL中的数据到 getCurrencyData功能。

与错误无关，但您也将错误数据设置为 currencySymbol ，因为您从 currencyArray 为其分配数据而不是 currencySymbolArray .