Aynchronous API call not returning data before variable initialization - swift

Question

I am segueing from an initial view to a second view. The first view consists of a text field for a user to enter their search term (account name). That name gets segued to the second view.
I then take this name, and make a call to the Riot API, to return details of their account (name, id, and account ID, level, etc.).
I then update the GUI labels with their credentials (name, id, level).
Now is where this process falls apart; the program does not wait for the API call to complete before it moves forward.
The step breakdown I want is essentially in this order:
1)Use the search term from the segue to call the Riot API
2)Update the GUI with the credentials
3)Initialize some variables with the credentials returned from the Riot API
Instead, this is happening:
1)Use the search term from the segue to call the Riot API
2)Initialize some variables (with credentials from the API (but it cant because they aren't returned yet))
3)Update the GUI with the credentials
The program is skipping forwards and not waiting for data to be returned.
I have come to the understanding that this way of calling the API is 'asynchronous', and that it will not wait for the data to be retrieved before it continues - and the DispatchQueue.main.async{} is useful so long as everything else you need to code follows within the braces.
If you append code after task.resume() it will not use the data retrieved from the call because it isn't returned yet.
My question is essentially: how do I make the 'let task = UrlSession.shared... task.resume() wait for the users credentials so I can then proceed forward with the rest of the code, sequentially - rather than embedding the rest of this view's code within the DispatchQueue.main.async{} braces?
import UIKit
class ViewControllerProfile: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
//test to see if we got the name from the segue:
print("from Segue: " + summonerName)
//execute on view load:
let theUser = Summoner(name: summonerName)
print(theUser.name!)
//API - Summoners Details By Summoner Name:
//Construct request for name in secondViewController(PROFILE)
let root:String = "https://euw1.api.riotgames.com"
let entryPoint:String = "/lol/summoner/v3/summoners/by-name/"
let key:String = "?api_key=<key>"
//theUser.name! is a search term (players name)
let completeURL = root + entryPoint + theUser.name! + key
let urlRecieved = URL(string: completeURL.addingPercentEncoding(withAllowedCharacters: CharacterSet.urlQueryAllowed)!)
let task = URLSession.shared.dataTask(with: urlRecieved!){ (data, response, error) in
if error != nil{
print("ERROR")
}
else{
if let content = data{
do{
//Array:
let myJson = try JSONSerialization.jsonObject(with: content, options: JSONSerialization.ReadingOptions.mutableContainers) as! [String:Any]
//We now extract the required information from the JSON output with keys:
//Class generics for future parsing:
let summonerID = myJson["id"] as? UInt64
let usersSummonerID:Int = Int(summonerID!)
print(usersSummonerID)
let accountID = myJson["accountId"] as? UInt64
let usersAccountID = Int(accountID!)
print(usersAccountID)
//Required elements for Profile Labels:
let extractName = myJson["name"] as? String
let extractLevel = myJson["summonerLevel"] as? UInt64
//We need to convert the extractLevel variable from UInt64 to String to update a label without an optional:
let usersLevel:String = "\(extractLevel!)"
//We update the gui now using the data we got from the API call:
DispatchQueue.main.async {
//We dispatch the user interface updates to the main thread here:
self.summonerLevelLbl.text = ("Level: " + "\(usersLevel)")
self.summonerNameLbl.text = extractName
//We dispatch the api-returned userObject's attributes to the main thread for assignment here:
self.summonerNameMain = extractName!
self.summonerIDMain = usersSummonerID
self.accountIDMain = usersAccountID
print("dispatch completed\n\n")
//all future code goes here?
}
}
catch{
print("SOMETHING WENT WRONG WITH SERIALIZATION OF NAME X")
}
}
}
}
task.resume()
theUser.name = summonerNameMain
theUser.accountID = accountIDMain
theUser.summonerID = summonerIDMain
print("ASSIGNMENT TEST")
print(theUser.name!)
print(theUser.summonerID!)
print(theUser.accountID!)
}
#IBOutlet weak var summonerNameLbl: UILabel!
#IBOutlet weak var summonerRankLbl: UILabel!
#IBOutlet weak var summonerLevelLbl: UILabel!
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
//For Segue:
var summonerName = String()
//For Parsing:
var accountIDMain = Int()
var summonerIDMain = Int()
var summonerNameMain = String()
}
class Summoner:NSObject{
var name:String?
var summonerID:Int?
var accountID:Int?
var matchID:Int?
init(name: String){
self.name = name
}
}
After task.resume()
I want it to wait for the above code to complete before proceeding (let task = URLSession.shared.dataTask... up to task.resume())
Further API calls that require data from previous calls, will be necessary and preferably I would prefer to avoid embedding more code in the async.

Answer 1

Simply move these lines (and the print statements if you want):
theUser.name = summonerNameMain
theUser.accountID = accountIDMain
theUser.summonerID = summonerIDMain
to where you have your comment about "all future code".
Done.