feedvc.swift

import UIKit
import Parse
import ParseLiveQuery

import SDWebImage
import ActiveLabel
import MXParallaxHeader



class FeedVC: UITableViewController, ShopDetailDelegate {
    
    var subscription: Subscription<Post>!

    var postsQuery: PFQuery<Post> {
        return (Post.query()?
            .order(byAscending: "createdAt")) as! PFQuery<Post>
    }
    
    var client: Client {
        
        return ParseLiveQuery.Client.shared
    }
    var results = [Post]()
    
    
    //page size
    var page : Int = 10


    
    //Default func
    override func viewDidLoad() {
        super.viewDidLoad()

        
        tableView?.backgroundColor = UIColor(red: 0.0 / 255.0, green: 0.0 / 255.0, blue: 0.0 / 255.0, alpha: 1)

        // Automatic row height
        tableView.estimatedRowHeight = 450
        tableView.rowHeight = UITableViewAutomaticDimension
      
     
    
        // Start the subscription
        subscription = client.subscribe(postsQuery).handleSubscribe { [weak self]  (_) in
            // Fetch the objects on subscription to not miss any
            self?.fetchObjects()
            }.handleEvent { [weak self] (_, event) in
                self?.handleEvent(event: event)
        }
        
        
    }
 
    func index(ofResult result: Post) -> Array<Post>.Index? {
        return results.index(where: {
            $0.objectId == result.objectId
        })
    }

    func handleEvent(event: Event<Post>) {
        // Make sure we're on main thread
        if Thread.current != Thread.main {
            return DispatchQueue.main.async { [weak self] _ in
                self?.handleEvent(event: event)
            }
        }

        switch event {
        case .created(let obj),
             .entered(let obj):
            
            results.insert(obj, at: 0)
            tableView.insertRows(at: [IndexPath(row: 0, section: 0)], with: .automatic)
            
        case .updated(let obj):
            
            guard let index = index(ofResult: obj) else { break }
            results.remove(at: index)
            results.insert(obj, at: 0)
            tableView.moveRow(at: IndexPath(row: index, section: 0), to: IndexPath(row: 0, section: 0))
            tableView.reloadRows(at: [IndexPath(row: 0, section: 0)], with: .automatic)
            
        case .deleted(let obj),
             .left(let obj):
            
            guard let index = index(ofResult: obj) else { break }
            results.remove(at: index)
            tableView.deleteRows(at: [IndexPath(row: index, section: 0)], with: .automatic)
        
        }
    }
    
    func fetchObjects() {
        
        print("fetchObjects()")
        postsQuery.findObjectsInBackground().continue(with: BFExecutor.mainThread(), with: { (task) -> Any? in
            guard let objects = task.result as? [Post] else {
                return nil
            }
            self.results = objects
            self.tableView.reloadData()
            
            print("Got it!!!")
            
            print(objects)
            return nil
        })
    }

 
    
    
  
    

 
}