Wait for function to end in Swift - ios

Question

I have a function to get data with json and i append all the data to an array. I try to create semaphore and wait until sending a signal to semaphore to continue but it doesn't work(I'm not sure if i do it correct or not), then i saw a question in Stackoverflow, answer was creating a completion handler like that
func application(application: UIApplication!, performFetchWithCompletionHandler completionHandler: ((UIBackgroundFetchResult) -> Void)!) {
getUrunGrup(completionHandler)
}
so i changed my function like that
func getUrunGrup(completionHandler: ((UIBackgroundFetchResult) -> Void)!){
Alamofire.request(.GET, "http://213.136.86.160:27701/Thunder/DataService/GetUrunGrup")
.responseJSON {(request, response, jsonObj, error) in
if let jsonresult:NSDictionary = jsonObj as? NSDictionary{
if let result: AnyObject = jsonresult["Result"] {
let elementCount = result.count
for (var i = 0; i<elementCount; ++i){
if let name: AnyObject = result[i]["Adi"]!{
if let kod:AnyObject = result[i]["Kod"]!{
urunUstGrup.append(["Adi": "\(name)", "Kod": "\(kod)"])
println("getUrunGrup \(i)")
}
}
}
}
}
}
completionHandler(UIBackgroundFetchResult.NewData)
println("Background Fetch Complete")
}
But there is no answer for how should i call this function?

Answer 1

you have to pass your async function the handler to call later on,like this:
func application(application: UIApplication!, performFetchWithCompletionHandler completionHandler: ((UIBackgroundFetchResult) -> Void)!) {
loadShows(completionHandler)
}
func loadShows(completionHandler: ((UIBackgroundFetchResult) -> Void)!) {
//....
//DO IT
//....
completionHandler(UIBackgroundFetchResult.NewData)
println("Background Fetch Complete")
}
OR (cleaner way IMHO)
add an intermediate completionHandler
func application(application: UIApplication!, performFetchWithCompletionHandler completionHandler: ((UIBackgroundFetchResult) -> Void)!) {
loadShows() {
completionHandler(UIBackgroundFetchResult.NewData)
println("Background Fetch Complete")
}
}
func loadShows(completionHandler: (() -> Void)!) {
//....
//DO IT
//....
completionHandler()
}