Passing a document reference to a second view controller - swift

Question

Can someone please show me how I can make it so that when I click on a specific row in a tableView, a document reference is passed to a second ViewController allowing me to show the fields inside the subcollection "Friends". At the moment I can do this but without using autoID. Please may someone how I can do this using an autoID? Any help would be greatly appreciated, many thanks!!
Current Firebase Console
What I would like - Firebase Console
First ViewController
func loadData() {
db.collection("Users").getDocuments() { (querySnapshot, err) in
if let err = err {
print("Error getting documents: \(err)")
} else {
for document in querySnapshot!.documents {
let data = document.data()
let name = data["name"] as? String ?? ""
let newName = UsersNames(name: name)
self.nameArray.append(newName)
}
self.tableView.reloadData()
}
}
}
Second ViewController
func loadData() {
db.collection("Users").document("Hello").collection("Friends").getDocuments() { (querySnapshot, err) in
if let err = err {
print("Error getting documents: \(err)")
} else {
for document in querySnapshot!.documents {
let data = document.data()
let name = data["name"] as? String ?? ""
let details = data["details"] as? String ?? ""
let newFriends = Friends(friendName: name, friendDetails: details)
self.friendsArray.append(newFriends)
}
self.tableView.reloadData()
}
}
}

Answer 1

If you want to do it that way, firstly you need to add a documentID property to your UsersNames object:
struct UsersNames {
var documentID: String //<-- Add this
var name: String
}
Then update your loadData() function in your First VC to get the documentID from each Firestore document and append in into your Array:
for document in querySnapshot!.documents {
let data = document.data()
let documentID = document.documentID //<-- Add this
let name = data["name"] as? String ?? ""
let newName = UsersNames(documentID: documentID, name: name) //<-- Change this
self.nameArray.append(newName)
}
In First VC, you want to perform a Segue to your Second VC when a cell is selected, and pass the documentID for the selected object in your Array to the Second VC.
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
performSegue(withIdentifier: "SecondVC", sender: self)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let indexPath = tableView.indexPathForSelectedRow {
let destinationVC = segue.destination as! SecondVC
let documentId = nameArray[indexPath.row].documentID
destinationVC.documentID = documentID
}
}
In your SecondVC create a property to receive the documentID:
var documentID: String!
In your SecondVC loadData() function, you can now access the documentID that was passed from your First VC:
db.collection("Users").document(documentID).collection("Friends").getDocuments() { //..