如何将数据传递到从Firebase检索信息的闭包之外? [英] How to pass data out of a closure that retrieves info from Firebase?

问题描述

我正在尝试将从Firebase数据库中检索到的数据传递到我的单例字段中.数据是通过闭包接收的，在该闭包中，我正在将一些数据传递到我的单例属性中.如果我在闭包内部打印数据结构(在分配完所有内容之后)，则会得到期望的输出，但是如果在所有数据都应传递之后在初始化程序的末尾打印它，则该输出为空.

I'm trying to pass data that I've retrieved from my firebase database into a field of my singleton. The data is received via closure, and in that closure I'm passing some data into my singleton's properties. If I print the data structure inside the closure (after everything's been assigned) I get the output I'm expecting, but if I print it at the end of the initializer after all the data should've been passed in, it's empty.

import Foundation
import Firebase

class EmployeeList {
    static let sharedInstance = EmployeeList()
    var employeeDictionary: [String: [EmployeeData]]
    var ref: DatabaseReference!

    private init() {
        employeeDictionary = [String: [EmployeeData]]()
        ref = Database.database().reference()

        ref.child("employeeList").observeSingleEvent(of: .value, with: { snapshot in
            if let dictionary = snapshot.value as? [String: [String: AnyObject]] {
                for subsection in dictionary {
                    var subsectionEmployees: [EmployeeData] = []

                    for item in subsection.value {
                        self.ref.child("employeeList/\(subsection.key)/\(item.key)").observeSingleEvent(of: .value, with: { employeeSnapshot in
                            let employeeObject = EmployeeData(snapshot: employeeSnapshot)
                            subsectionEmployees.append(employeeObject)
                            self.employeeDictionary[subsection.key] = subsectionEmployees
                            //print(self.employeeDictionary) This print statement prints out the expected data every time another employee is appended
                        })
                    }
                }
            }
            //print(self.employeeDictionary) This print statement prints an empty data structure
        })
    }
}

推荐答案

从Firebase如下获取数据

get data from Firebase as Below

var messagedata = [String:AnyObject]()

 let databaseReff = Database.database().reference().child("message")

 databaseReff.queryOrdered(byChild: "fromId").queryEqual(toValue: self.recieverId).observe(.value, with: { snapshot in
      if snapshot.exists(){
           self.messagedata = snapshot.value! as! [String : AnyObject]        
           self.getAllMessagesSent(snapshot: self.messagedata)
      } else 
           self.getAllMessagesSent(snapshot: self.messagedata) //Function Created
      }
 })

将从Clousre提取的数据传递给字典，并将该字典传递给函数，并执行您想做的任何事情或使用转义块

pass the data fetched from Clousre to a dictionary and pass that dict to a function and do anything you want to do or use escaping blocks

func getAllMessagesSent(snapshot: [String:AnyObject]) {
     //data is here
}

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