Appending an array within a post rather than creating a new post - ios

Question

I am trying to make a comment section for my open source social media app. I have a table of posts. When you click a post in this table, it takes you to the MainViewController, where you can read the comments on those posts and post your own comment. The Post class is as follows:
import Foundation
class Post {
var id:String
var title: String
var text:String
var createdAt:Date
var comment: [String] = []
init(id: String, title: String,text:String, timestamp:Double, comment: [String] = []) {
self.id = id
self.title = title
self.text = text
self.createdAt = Date(timeIntervalSince1970: timestamp / 1000)
}
static func parse(_ key:String, data:[String:Any]) -> Post? {
if let title = data["text"] as? String,
let text = data["title"] as? String,
let timestamp = data["timestamp"] as? Double {
return Post(id: key, title: title, text: text, timestamp:timestamp, comment: [])
}
return nil
}
}
And the MainTextViewController has the following code:
import Foundation
import UIKit
import Firebase
class MainTextView: UIViewController, UITextViewDelegate{
#IBOutlet weak var titleText: UILabel!
#IBOutlet weak var mainText: UILabel!
#IBOutlet weak var commentsTable: UITableView!
#IBOutlet weak var commentPlaceHolder: UILabel!
#IBOutlet weak var newCommentLabel: UITextView!
weak var delegate:NewPostVCDelegate?
#IBAction func reply(_ sender: UIButton) {
// Firebase code here
let postRef = Database.database().reference().child("posts").childByAutoId()
let postObject = [
"comment": newCommentLabel.text,
"timestamp": [".sv": "timestamp"]
] as [String : Any]
postRef.setValue(postObject, withCompletionBlock: { error, ref in
if error == nil {
self.delegate!.didUploadPost(withID: ref.key!)
self.dismiss(animated: true, completion: nil)
} else {
// Handle error
}
})
newCommentLabel.text = String()
commentPlaceHolder.isHidden = false
}
var post: Post?
// MARK: - View Controller LifeCycle
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
self.setMain()
}
override func viewDidLoad() {
super.viewDidLoad()
print(delegate!)
commentsTable.dataSource = post?.comment as? UITableViewDataSource
newCommentLabel.delegate = self
}
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return post!.comment.count
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = UITableViewCell()
let label = UILabel(frame: CGRect(x:0, y:0, width:200, height:50))
cell.addSubview(label)
return cell
}
// UITableViewDelegate Functions
func tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
return 50
}
private func setMain() {
guard let post = self.post else {
return
}
titleText.text = post.text
mainText.text = post.title
}
func textViewDidChange(_ commentView: UITextView) {
commentPlaceHolder.isHidden = !newCommentLabel.text.isEmpty
}
}
Here is my database structure:
{
"posts" : {
"-LhaxLOSY3UI7tDUrCA_" : {
"text" : "Nelson",
"timestamp" : 1560800488059,
"title" : "Hey\t"
},
"-LhaxbnjgDP7tdb7Eq_4" : {
"text" : "Lol",
"timestamp" : 1560800558514,
"title" : "How’s it going"
},
"comment" : {
"comment" : "Howdy"
}
}
}
I want that when I make a comment, it appends the comments array for the post with a new comment. Then everyone can see the comments in the commentsTable as a collection of strings from the array with the oldest one on top.
At the moment, creating a new comment makes a new post in Firebase with just a comment as a single string and a timestamp. How would you fix this issue so that the post button appends the table and the commentsTable shows the strings from the array? Let me know if you need me to post more details. Thank you for the help.

Answer 1

Without going overboard with a bunch of code, conceptually, if you want to have a series of posts, and then each post can additionally have comments, here's one option for a structure.
posts
post_id_0
text: "some text"
timestamp: "20190601"
title: "post title"
post_uid: "uid_0"
comments
comment_id_0
belongs_to_post: "post_id_0"
comment: "a comment about the post"
timestamp: "20190601"
comment_uid: "uid_49"
comment_id_1
belongs_to_post: "post_id_0"
comment: "check out that first post!"
timestamp: "20190602"
comment_uid: "uid_102"
users
uid_0
name: "Leroy"
then attach observers to posts and comments. When a new post is posted, you'll be notified of that post and can add it to your tableView datasource and refresh the tableView.
When a new comment is added, you'll be notified of that comment and add it to the comments dataSource and reload the comments tableView. To add a new post:
let thisPostRef = your_firebase.posts.childByAutoId()
thisPostRef.setValue(your_post_data)
and to add a comment
let postKey = the_post.key
let commentRef = your_firebase.comments.childByAutoId()
commentRef.setValue(your_comment_data)
and your_comment_data would include a child node 'belongs_to_post: postKey'
You can also watch for comments on certain posts, made by certain users or even query for comments by date or in a date range.
Code wise, both posts and comments nodes are created with .childByAutoId - it's best practice to disassociate node keys from the data they contain, unless it going to be static data, like a uid.
If you want to add a bit more flexibility, you could keep a child node within each posts of it's related comments as well.
posts
post_id_0
text: "some text"
timestamp: "20190601"
title: "post title"
post_uid: "uid_0"
comments:
comment_id_0: true
comment_id_1: true
but that depends on what kinds of queries you want to run.
Note: I separate the comments structure from the posts the posts node as denormalizing your data is very beneficial when running queries.