使用Swift在Firebase中读取快照中的数组

Question

Need help trying to read an array of this form:

As far as I tried, I got this

let defaults = UserDefaults.standard
let userUuid = defaults.string(forKey: defaultsKeys.keyOne)
let ref = FIRDatabase.database().reference().child("images").child("\(userUuid!)")
let filterQuery = ref.queryOrdered(byChild: "uuid").queryEqual(toValue: "\(uuid)") // where uuid is a value from another view

filterQuery.observe(.value, with: { (snapshot) in
        for images in snapshot.children {
            print(images)
        }
})

But I receive nothing. I want to read the images' links to show them in the view controller.

Answer 1

1. Make sure that the uuid var in the line below is not an optional value (or if it is, unwrap it) because otherwise you'll be querying to compare to "Optional(myUuidValue)" instead of "myUuidValue"

    let filterQuery = ref.queryOrdered(byChild: "uuid").queryEqual(toValue: "\\(uuid)") 

2. The snapshot in the line below contains more than just the images, it has all the other children under that uuid

    filterQuery.observe(.value, with: { (snapshot) in }) 

   So extract the images like this:

    filterQuery.observe(.value, with: { (snapshot) in let retrievedDict = snapshot.value as! NSDictionary let innerDict = retrievedDict["KeyHere"] as! NSDictionary // the key is the second inner child from images (3172FDE4-...) let imagesOuterArray = userDict["images"] as! NSArray for i in 0 ..< imagesOuterArray.count { let innerArray = imagesOuterArray[i] as! NSArray for image in innerArray { print(image as! String) } } }) 

   Clarification: cast all the children of the uuid as an NSDictionary , then extract the nested arrays using those two for-loops

Update Thanks to Jay for pointing out the error! Also, as Jay suggested, consider restructuring your database and replacing those arrays with dictionaries that perhaps contain the URL, path (for deleting purposes if you need that), and timestamp of each image.

Answer 2

After strugling for the answer, got this code works

let ref = FIRDatabase.database().reference().child("images").child("\(userUuid!)")
    let filterQuery = ref.queryOrdered(byChild: "identifier").queryEqual(toValue: "\(identifier)")

    filterQuery.observe(.value, with: { (snapshot) in
        for child in snapshot.children {
            if (child as AnyObject).hasChild("images") {
                let images = (images as AnyObject).childSnapshot(forPath: "images").value! as! NSArray
                for i in images {
                    for j in i as! [AnyObject] {
                        let url = NSURL(string: j as! String)
                        //Then downloaded the images to show on view
                        URLSession.shared.dataTask(with: url! as URL, completionHandler: { (data, response, error) in
                            if error != nil {
                                print(error)
                                return
                            }
                            //Code to show images..

                        }).resume()
                    }


                }
            }
        }

    })

Can i receive feedback about this?