获取单个数组项目

Question

I am reading data from a firebase DB and storing it in a message object, How can I then access each element in that array? ie how can I use the City string as I wish to assign that to a label. Same with each other element in the array.

    firebaseDB.collection("user").document(key).collection("address").getDocuments() { (querySnapshot, err) in
        if let err = err {
            print("Error getting documents: \(err)")
        }
        else {
            self.dataArr.removeAll()
            for document in querySnapshot!.documents {
                //print("\(document.documentID) => \(document.data())")
                let msgdata = document.data() as! [String:Any]
                var msgObj = Details()
                if let city = msgdata["city"] as? String {

                    msgObj.city = city
                }

                if let country = msgdata["country"] as? String {

                    msgObj.country = country
                }
                if let county = msgdata["county"] as? String {

                    msgObj.county = county
                }

                if let lineOne = msgdata["lineOne"] as? String {

                    msgObj.lineOne = lineOne
                }
                if let lineTwo = msgdata["lineTwo"] as? String {

                    msgObj.lineTwo = lineTwo
                }
                if let postCode = msgdata["postCode"] as? String {

                    msgObj.postCode = postCode
                }
                self.dataArr.append(msgObj)

            }


        }
    }

I will need to access each element as I have another function which will take each element and place it on a label in my ViewController

Something like this is what I wish to have

func DisplayAddress(){
 city.text = city
 postCode.text = postCode
}

Answer 1

I may be totally reading the question wrong but in trying to read into your question, I think the terminology may be where clarification is needed; Object vs Array

An object has properties - lets examine the Details() object

var msgObj = Details()

which contains address information for one user. So conceptually this is how it would be represented in FireStore

users
  this_user
    address
      city: "some city"
      country: "some country"
      county: "some county"
      line1: "line one"

the 'documents' are the items stored within the address collection

  city: "some city"
  country: "some country"
  county: "some county"
  line1: "line one"

and your Details() object has properties that correspond to those documents and stores them as properties within the object; city, county etc

 msgObj.city = city
 msgObj.country = country

On the other hand, an array contains a series of objects , not properties. eg an array would generally not contain city, country etc, but it would contain a series of Details() objects and each of those Detail() objects has it's properties of city, country etc. For example, suppose you want to work with addresses of several different users - you would create a Details() object for each user, which contains their address information and append each one to an array.

self.dataArry[0] = the Details() objects of one user
self.dataArry[1] = the Details() object of another user
self.dataArry[2] = the Details() object of a third user

You could then, for example, display the users within a certain radius of this user, or send them all an email etc.

To answer your question, if you are working with a single users address information there is no need for an array, you can simply store it as a single Details() object variable within the class.

class ViewController: UIViewController {
    var myUserAddress = Details()

    func to get this users address documents from FireStore {
        if let city = msgdata["city"] as? String {
           self.myUserAddress.city = city
        }
        if let country = msgdata["country"] as? String {
           self.myUserAddress.country = country
        }
        //remember that the properties are only valid from here on
        //as FireStore is asychronous
        self.DisplayCity()
        self.DisplayLocation()
    }

    //and then later on when you want to display those properties
    func DisplayCity() {
      let city = self.myUserAddress.city
      print(city)
    }
    func DisplayLocation() {
      let lon = self.myUserAddress.logitude
      let lat = self.myUserAddress.latitude
      //show the location on a map via lon & lat
    }