Firebase setValue（）在模拟器中工作，但不在设备上，任何人都知道为什么？(Firebase setValue() works in simulator but not on device, anyone know why? iOS 10, Swift 3.1)

 此代码按照模拟器中的要求保存到Firebase数据库，但完成处理程序不会在设备上调用。 有谁知道为什么或可能的修复？ 
 
var customersRef : FIRDatabaseReference {
            return dbRef.child("customers")
    }


func saveDealData(dealBuilder: DealBuilder, errMsgHandler: ErrMsgHandler?) {
            print("Shown in log in sim and device")
            customersRef.child(u.id!).child("deals").childByAutoId().setValue("true") { error, dbRef in
                    print("Is called for sim but not device")

            }
    }
 
 我试图摆脱尾随的关闭，并将setValue（）放在里面，但是同样的情况发生了： 
 
  customersRef.child(u.id!).child("deals").childByAutoId().setValue("true", withCompletionBlock:  { error, dbRef in
                    print("Is called in sim but not device")
            })

This code saves to the Firebase database as required in the simulator but the completion handler doesn't get called on the device. Does anyone know why or of a possible fix? 
 
var customersRef : FIRDatabaseReference {
            return dbRef.child("customers")
    }


func saveDealData(dealBuilder: DealBuilder, errMsgHandler: ErrMsgHandler?) {
            print("Shown in log in sim and device")
            customersRef.child(u.id!).child("deals").childByAutoId().setValue("true") { error, dbRef in
                    print("Is called for sim but not device")

            }
    }
 
I've tried getting rid of trailing closure and putting inside setValue() as below, but the same happens:
 
  customersRef.child(u.id!).child("deals").childByAutoId().setValue("true", withCompletionBlock:  { error, dbRef in
                    print("Is called in sim but not device")
            })

原文：https://stackoverflow.com/questions/43428588