ios - Swift 自定义 updateUI() 函数在 viewDidLoad 上不起作用

Question

我正在开发一个应用程序，它应该从我的服务器请求一些数据。我使用 Alamofire 来执行此操作，然后使用 SWXMLHash 来解析 XML 数据。有两个 View Controller ，在第一个 View Controller 上我可以编写一个发货编号，然后重写函数prepareForSegue并将该编号发送到下一个 View Controller ，该 View Controller 应该显示来自服务器的数据并在viewDidLoad上更新UI，但事实并非如此。哪里有问题？

我的类(class):

class Shipment {
    private var _shipmentNumber: String!
    private var _shipmentStatus: String!
    private var _trackURL: String!

    var shipmentNumber: String {
        if _shipmentNumber == nil {
            _shipmentNumber = ""
        }
        return _shipmentNumber
    }

    var shipmentStatus: String {
        if _shipmentStatus == nil {
            _shipmentStatus = ""
        }
        return _shipmentStatus
    }

    init(spNumber: String) {
        self._shipmentNumber = spNumber

        _trackURL = "..."
    }

    func requestXmlInformation(completed: DownloadComplete) {
        let url = NSURL(string: _trackURL)!
        Alamofire.request(.GET, url).responseData { response in

            if let xmlToParse = response.data as NSData! {
                let xml = SWXMLHash.parse(xmlToParse)

                do {
                    let xmlSpWeight = try xml["fmresultset"]["resultset"]["record"]["field"].withAttr("name", "ТotalWeight")["data"].element!.text! as String

                    self._shipmentStatus = xmlSpStatus
                    print(self._shipmentStatus)
                } catch let err as NSError {
                    print(err.debugDescription)
                }
            }
        }
    }
}

我的第二个 View Controller

@IBOutlet weak var numberLbl: UILabel!
@IBOutlet weak var weightLbl: UILabel!
@IBOutlet weak var statusLbl: UILabel!
@IBOutlet weak var packageQtyLbl: UILabel!

var shipment: Shipment!

override func viewDidLoad() {
    super.viewDidLoad()
    shipment.requestXmlInformation { () -> () in
        self.updateUi()
        print(self.statusLbl.text)
    }
  }

更新UI函数:

func updateUi() {
    numberLbl.text = shipment.shipmentNumber
    weightLbl.text = shipment.shipmentWeight
    statusLbl.text = shipment.shipmentStatus
    packageQtyLbl.text = shipment.shipmentPackageQty
}

它在终端中打印数据，但我认为 updateUI 功能不起作用。

Answer 1

确保在主线程上调用 requestXmlInformation 闭包中的代码。您不应该在后台线程中更新 UI。

shipment.requestXmlInformation { () -> () in
  dispatch_async(dispatch_get_main_queue(), { () -> Void in
        self.updateUi()
        print(self.statusLbl.text)
  })
}

此外，您似乎没有在 requestXmlInformation 方法中的任何位置调用完整的闭包