用firebase完成处理程序不起作用

Question

我尝试从Firebase获取值，然后我想打印执行第二行的代码，然后是TRUE。

但是订单是完全错误的。我在做什么错？

override func viewDidLoad() {
        super.viewDidLoad()
        

        method(arg: true, completion: { (success) -> Void in
            print("Second line of code executed")
            if success { // this will be equal to whatever value is set in this method call
                  print("true")
            } else {
                 print("false")
            }
        })
        
    }

    func method(arg: Bool, completion: (Bool) -> ()) {
        let userID = Auth.auth().currentUser!.uid
        let database = Database.database().reference()
        database.child("user/\(userID)/abonniertePoi/").observe(.value, with: { snapshot in
            for child in snapshot.children.allObjects as! [DataSnapshot] {
                myFeed.myArray1.append(child.key)
            }
            print(myFeed.myArray1)
            
        })
        completion(arg)
    }

它首先打印第二行执行，然后执行firebase请求，然后说为true。