Re-execute while loop after completion handler has been returned - swift

Question

I have a while loop i wish to keep executing if the returned number is 0. The problem is currently have is that the loop never stops since it doesnt wait for the completion handler to return its results (which takes a couple seconds). How can i only re execute the while loop after the if statement has been completed?
while loop
var empty = true
override func viewDidLoad() {
repeat {
str = iFunctions.generateRandomStringWithLengthOf(4) as String
iFunctions.getServerData(str){(msg)
in
if (msg > 0){
self.empty = false
print("not empty")
}
else{
print("empty")
}
self.count = msg!
print(self.count)
}
} while(empty)
}
function
func getServerData(q: String, completionHandler: (Int?) -> ()) -> () {
let params = [
"term": q
]
Alamofire.request(.GET, "URL", parameters: params)
.responseJSON { response in
if response.result.error == nil {
let json = JSON(response.result.value!)
//add data to struct
completionHandler(json["results"].count)
}
}
}

Answer 1

You shouldn't do this with a loop. That's the whole point of Alamofire, so you don't have to deal with threads and loops. You're working with high level instructions: callbacks.
It's actually very easy to solve your problem:
var empty = true
override func viewDidLoad() {
self.tryGettingDataFromServer()
}
func tryGettingDataFromServer(){
str = iFunctions.generateRandomStringWithLengthOf(4) as String
iFunctions.getServerData(str){(msg) in
if (msg > 0){
self.empty = false
print("not empty")
}
else{
// The closure keeps a reference to self and calls
// the tryGettingDataFromServer again if "empty"
// It will happen infinitely until "not empty"
self.tryGettingDataFromServer()
}
self.count = msg!
print(self.count)
}
}