从Firebase检索对象

Question

I'm working on simple program - I create objects of products and then I count their calories.

I want to count sum of all calories of my products.

I've created a method, allowing me to save data properly in Firebase, but I got stuck while retrieving them:

import UIKit
import Firebase

class TotalViewController: UIViewController {

    var products = [Products]()

    @IBOutlet weak var calotyCounter: UILabel!


    override func viewDidLoad() {
        super.viewDidLoad()

        DataService.dataService.PRODUCT_BASE.observeEventType(.Value, withBlock: { snapshot in

            print(snapshot.value)

            self.products = []

            if let snapshots = snapshot.children.allObjects as? [FIRDataSnapshot] {

                for snap in snapshots {

                    if let postDictionary = snap.value as? Dictionary<String, AnyObject> {

                        let key = snap.key

                        let product = Products(key: key, dictionary: postDictionary)


                    }
                }
            }

            self.updateCalory()

        })


        // Do any additional setup after loading the view.
    }

    func updateCalory() {

        var CaloryArray: [Int] = []

        for product in products {

            CaloryArray.append(Int(product.productCalories))

        }

        print (CaloryArray)

        calotyCounter.text? = String(CaloryArray.reduce(0, combine: +))

    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

I got an empty array, instead of array of objects callory value.

Here is my model of Products.I made it through dictionary

import Foundation
import Firebase

class Products {

    private var _productName: String!

    private var _productCalories: Int!


    var productName: String {

        return _productName

    }

    var productCalories: Int {

        return _productCalories
    }

    init(key: String, dictionary: Dictionary<String, AnyObject>) {


        if let calories = dictionary["calories"] as? Int {

            self._productCalories = calories
        }

        if let name = dictionary["name"] as? String {

            self._productName = name
        }


    }


}

What I'm doing wrong?

Answer 1

You have only initiated the empty array of products in viewDidLoad()

self.products = []

and not assigning any thing to it anywhere. thats why you are getting the empty array.

and on updateCalory() method you are looping on empty array (array with zero items)

EDIT 1

you must append the product ie

let product = Products(key: key, dictionary: postDictionary)

to your products array in loop. like this

for snap in snapshots {

                if let postDictionary = snap.value as? Dictionary<String, AnyObject> {

                    let key = snap.key

                    let product = Products(key: key, dictionary: postDictionary)
                    self. products.append(product) // add this line

                }
            }