Value changes on scroll UITableView

Question

I have a UITableView with a button in that's toggled depending on whether a user 'favorites' a post or not. Everything works well, except for when the table view is scrolled, the button changes. Here's my code:

func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    guard let feed = self.feed else {
        return 0
    }
    return feed.count
}

func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    if feed!.count > 9 {
        if indexPath.row == feed!.count - 1 {
            self.loadMorePosts()
        }
    }

    if hasImageAtIndexPath(indexPath) {
        return imageCellAtIndexPath(indexPath)

    } else {
        return basicCellAtIndexPath(indexPath)
    }

}

func hasImageAtIndexPath(indexPath:NSIndexPath) -> Bool {
    let post = self.feed?[indexPath.row]

    if post?.image?.isEmpty == false {
        return true
    }

    return false
}

func imageCellAtIndexPath(indexPath:NSIndexPath) -> PostCellImage {
    let cell:PostCellImage = self.tableView.dequeueReusableCellWithIdentifier("imageCell", forIndexPath: indexPath) as! PostCellImage


    if let post = self.feed?[indexPath.row] {
        let likedPost = post.hasFavorited

        if likedPost == true {
            if let favoriteCount = post.favoriteCount {
                let count = String(favoriteCount)
                cell.likeButton.setTitle(count, forState: .Normal)
                cell.likeButton.setImage(UIImage(named: "liked"), forState: .Normal)
                cell.likeButton.setTitleColor(UIColorFromRGB("A61224"), forState: .Normal)
                cell.likeButton.addTarget(self, action: "unfavoritePost:", forControlEvents: UIControlEvents.TouchUpInside)
                cell.likeButton.tag = post.id!
            }
        } else {
            if let favoriteCount = post.favoriteCount {
                let count = String(favoriteCount)
                cell.likeButton.setTitle(count, forState: .Normal)
                cell.likeButton.addTarget(self, action: "favoritePost:", forControlEvents: UIControlEvents.TouchUpInside)
                cell.likeButton.tag = post.id!
            }
        }
    }

    return cell
}

Favorited Posts Array

var favoritedPosts =  [Int]()

Table View

if let likedPost = post.hasFavorited {
    if likedPost == true {
        self.favoritedPosts.append(indexPath.row)             
        print(self.favoritedPosts)
    }
}

if self.favoritedPosts.contains(indexPath.row) {
    let count = String(post.favoriteCount)
    cell.likeButton.setTitle(count, forState: .Normal)
    cell.likeButton.setImage(UIImage(named: "liked"), forState: .Normal)
    cell.likeButton.setTitleColor(UIColorFromRGB("A61224"), forState: .Normal)
    cell.likeButton.addTarget(self, action: "unfavoritePost:", forControlEvents: UIControlEvents.TouchUpInside)
    cell.likeButton.tag = post.id!     
} else {
    let count = String(post.favoriteCount)
    cell.likeButton.setTitle(count, forState: .Normal)
    cell.likeButton.addTarget(self, action: "favoritePost:", forControlEvents: UIControlEvents.TouchUpInside)
    cell.likeButton.tag = post.id!        
}  

Answer 1

This might be cased by the table view cell reuse. It turns out that your code set the likeButton.image when the post is a favorited post but did not remove the image when the post is not a favorited one. So when the first time each cell is loaded into tableView every thing works fine. However, when scrolling the tableView, when those cells with favorite image set moves out of the screen area, they will be reused for the cell scrolling in. Thus if this kind of cell is reused by a post that is even not favorited, the image will still be there.

There is a prepareForReuse method for UITableViewCell, it gives you the chance to reset the contents before a cell is being reused.