Set a childByAutoId value in Firebase data service class to be retrieved in another class

Hopefully I can make this more clear than my title. I created a FirebaseService class. In it I will create all of the methods for saving and retrieving data. I don't want to have to make a firebase reference in any other class. I simply want to reference this class to do that. If this isn't possible, please let me know so I don't move forward with it. Below is my FirebaseService class...

import UIKit
import Firebase

class FirebaseService: NSObject {

    let ref = FIRDatabase.database().reference()
    var id = String()


    func savePost(post:[String:AnyObject]) {
        let postRef = ref.child("posts").childByAutoId()
        id = postRef.key
        postRef.setValue(post)

    }



}

I want to be able to retrieve id from the FirebaseService class and have it actually use the value of childByAutoId (the post's randomly generated id in Firebase) when I save a post so I can save it as a value in post called "id". However, right now when I save it, I get an intended random id generated for the post as a whole but I don't get that value in my "id" key.

func postPost() {
    post.id = FirebaseService().id
    post.textContent = textView.text
    post.name = "Michael Williams"
    post.profileImageName = "cool"
    post.imageContentName = "coffee"
    post.createdDate = convertCurrentTimeToString()
    let postArray:[String:AnyObject] = ["name":post.name!, "profileImageName":post.profileImageName!, "textContent":post.textContent!, "imageContentName":post.imageContentName!, "createdDate":post.createdDate!, "id":post.id!]
    dismissViewControllerAnimated(true) {
        FirebaseService().savePost(postArray)
    }
}

Firebase database scheme:

• Posts "randomly generated id"

  • name: "John Doe"

  • id: same randomly generated id as above

  • postText: "Blah Blah"

Again, all I am getting for id is an empty string when I run the postPost() function.