my first and successful implementation of DispatchGroup in Swift. I'm still shaky on why it works, but it does. 🤷

DispatchGroup.swift

func constructUsers() {
        print("#ChatListTVC Starting constructUsers()")
        
        let group = DispatchGroup()
        
        for otherUserUid in userUids {
            group.enter() // entering the closure
            User.getBy(uid: otherUserUid, completion: { (user) in
                self.users.append(user)
                print("Chat List appended: \(user.firstName)")
                group.leave() // thread should leave here to run group.notify
            })
        }
                
        group.notify(queue: .main) {
            print("~~Reloading Chat List tableview~~")
            self.tableView.reloadData()
        }
    }