How to force Swift to wait the previous code is finished? - swift

Question

I just began learning Swift, I am working with an API behind, the problem is that : Swift don't wait my function finish therefore my last function appears like no code was done before.
import Foundation
import UIKit
import Alamofire
import SwiftyJSON
// Classes
class User {
init(data: Any) {
self.sex = JSON(data)["sex"].string!
print(self.sex)
}
var id: Int = 1
var online: Bool = false
var picture: String = ""
var sex: String = "Male"
}
// Fonctions
func getBackground(_ apiURL: String, completion : #escaping(_ :Any) -> Void) {
// Requête API avec Alamofire + SwiftyJSON
AF.request(apiURL, method: .get).validate().responseJSON { response in
switch response.result {
case .success(let value):
let jsonData = JSON(value)
completion(jsonData["results"])
case .failure(let error):
print(error)
}
}
}
// Requête de connexion
getBackground("https://x..me", completion: { response in
let user = User(data: response)
})
print(String(user.id) + ": " + String(user.online!))
Screenshot here
I have this error: "Use of unresolved identifier 'user'", I guess that Swift don't get the fact that User was defined previously
All my work works perfectly with my API, the "self.sex" is set and showed when I build the code.
But I'm still "locked" like I can't do nothing after this code because Swift don't want to wait.
I tried the function async and sync but then, all my next code has to be under a function...
Thanks in advance

Answer 1

There's no need to wait.
Put the print line – and the code which proceeds the user – in the completion closure
getBackground("https://a.clet.me", completion: { response in
let user = User(data: response)
print(String(user.id) + ": " + String(user.online!))
})
The error Use of unresolved identifier 'user' occurs because the local variable user is only visible inside the scope ({}) of its declaration.

Answer 2

So, this problem is all about variables life cycle.
// This happens first
getBackground("https://a.clet.me", completion: { response in
let user = User(data: response)
// This happens third, once the request has completed.
// user exists here.
// Only after this moment you should handle anything related to the user
})
// This happens second
// user DOESN'T exist here, swift will move on