Swift custom updateUI() function does not work on viewDidLoad - ios

Question

I'm working on an app, that should request some data from my server. I'm using Alamofire to do that, and then use SWXMLHash to parse the XML data. There are two View Controllers, on the first one I can write a shipment number, then override function prepareForSegue and send that number to the next View Controller that should display data from server and updateUI on viewDidLoad, but it does not. Where is a problem?
My 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)
}
}
}
}
}
My Second 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)
}
}
updateUI function:
func updateUi() {
numberLbl.text = shipment.shipmentNumber
weightLbl.text = shipment.shipmentWeight
statusLbl.text = shipment.shipmentStatus
packageQtyLbl.text = shipment.shipmentPackageQty
}
It prints data in terminal but i think updateUI function does not work.

Answer 1

Make sure that the code in your requestXmlInformation closure is called on the main thread. You shouldn't update the UI in background threads.
shipment.requestXmlInformation { () -> () in
dispatch_async(dispatch_get_main_queue(), { () -> Void in
self.updateUi()
print(self.statusLbl.text)
})
}
Also, you don't seem to call the complete closure anywhere in your requestXmlInformation method