var a = 0 var b = 0 let group = DispatchGroup() group.enter() DispatchQueue.main.async { FireStore.getDocument("Users", "") { (doc, v) in a = 1 group.leave() } } group.enter() DispatchQueue.main.async { FireStore.getDocument("Users", "") { (doc, v) in b = 1 group.leave() } } group.notify(queue: .main) { print("a = ", a) print("b = ", b) }