Ribbit/Swift clone : Reusable UITableViewCells change after I scroll

          import UIKit
     import QuartzCore

     class WallTableViewController: UITableViewController, UINavigationControllerDelegate {

    @IBOutlet var posterAvatar: UIImageView!

override func preferredStatusBarStyle() -> UIStatusBarStyle {
    return UIStatusBarStyle.LightContent
}


var timeLineData:NSMutableArray = NSMutableArray ()
var followedFriends:NSMutableArray = NSMutableArray ()

func loadUser () {

    followedFriends.removeAllObjects()
    var friendsRelation: AnyObject! = PFUser.currentUser().objectForKey("KfriendsRelation")


    var findUser : PFQuery = friendsRelation.query()


    findUser.findObjectsInBackgroundWithBlock { (objects:[AnyObject]!, error:NSError!) -> Void in
        if !(error != nil) {
            // The find succeeded.
            println("succesfull load Users")
            // Do something with the found objects
            for object  in objects  {
                self.followedFriends.addObject(object)
                println("users added to userlist")

                for item in self.followedFriends {
                    println(item)                    }
            }
            self.tableView.reloadData()
        } else {
            // Log details of the failure
            println("error loadind user ")

        }

    }
}


func loadPost () {

   timeLineData.removeAllObjects()

    let currentUser = PFUser.currentUser()

        var findPost:PFQuery = PFQuery(className: "UserPost")


    //query for the friends of the user
    var friendsRelation: AnyObject! = PFUser.currentUser().objectForKey("KfriendsRelation")
    var findFriends : PFQuery = friendsRelation.query()

    //using the friends from the query above, we find all the posts of the friends of the current user
    var findPosts:PFQuery = PFQuery(className: "UserPost")
    findPosts.whereKey("from", matchesQuery:findFriends)
    findPost.orderByDescending("createdAt")

    //run the query
    findPosts.findObjectsInBackgroundWithBlock { (objects:[AnyObject]!, error:NSError!) -> Void in
        if !(error != nil) {
            //found posts
            for object  in objects  {
                self.timeLineData.addObject(object)
            }
            self.tableView.reloadData()
        } else {
            // Log details of the failure
            println("error loadind posts ")

        }

    }
    }
override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
    return 1
}

 override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return timeLineData.count
}

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {

    let cell:WallTableViewCell = tableView.dequeueReusableCellWithIdentifier("cell", forIndexPath: indexPath) as WallTableViewCell

    let userPost:PFObject = self.timeLineData.objectAtIndex(indexPath.row) as PFObject

    //define the username

    var findUser:PFQuery = PFUser.query()
    findUser.whereKey("objectId", equalTo: userPost.objectForKey("from").objectId)

    findUser.findObjectsInBackgroundWithBlock{
        (objects:[AnyObject]!, error:NSError!) -> Void in

        if error == nil {
            if let user:PFUser = (objects as NSArray).lastObject as? PFUser {
                cell.usernameLabel.text = user.username

                // define avatar poster

                if let avatarImage:PFFile = user["profileImage"] as? PFFile {
                    avatarImage.getDataInBackgroundWithBlock{(imageData:NSData!, error:NSError!)-> Void in

                        if !(error != nil) {

                            let image:UIImage = UIImage(data: imageData)


                            cell.posterAvatar.image = image as UIImage
                            cell.posterAvatar.layer.cornerRadius = 24
                            cell.posterAvatar.clipsToBounds = true

                        }

                    }
                }
                else {
                    cell.posterAvatar.image = UIImage(named: "Avatar-1")
                    cell.posterAvatar.layer.cornerRadius = 24
                    cell.posterAvatar.clipsToBounds = true
                }
            }

        }

    }

    //define the imagepost

    let imagesPost:PFFile = userPost["imageFile"] as PFFile


    imagesPost.getDataInBackgroundWithBlock{(imageData:NSData!, error:NSError!)-> Void in

        if !(error != nil) {

            let image:UIImage = UIImage(data: imageData)



            cell.imagePosted.image = image as UIImage


        }
        else {
            println("error")
        }
    }

    return cell
}


override func viewDidAppear(animated: Bool) {
    var currentUser = PFUser.currentUser()
    if (currentUser != nil) {
        println("User allready logued")
    }

    else {
        // Show the signup or login screen

        self.performSegueWithIdentifier("goToLogIn", sender: self)
    }

}

override func viewDidLoad() {
   super.viewDidLoad()


}


override func viewWillAppear(animated: Bool) {
    self.tableView.separatorColor = UIColor.whiteColor()

    tabBarController?.tabBar.tintColor = UIColor.whiteColor()
    self.loadUser()
    self.loadPost()


}