CODEWITHSUNDEEP
iosswiftuitableview
aejhyun
aejhyun

Reputation: 612

Extremely weird behavior with table cells when going off screen

Here is the really weird behavior. When the table view is first loaded, it looks like this:

enter image description here

Now, when I scroll down and then scroll back up, the buttons appear on cells that didn't have buttons on them before! Like so:

enter image description here

I know this has to do with "This is the intended behaviour of a UITableView. The whole point of a UITableView is to queue up cells that are needed and release cells that aren't needed to manage memory" as described in this post: UITableView in Swift: Offscreen cells are not pre-loaded.

Here is my code:

var messages = [String]()

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCellWithIdentifier("cell", forIndexPath: indexPath) as! CathyTaskLogTableViewCell

    if messages[indexPath.row] != "" {
        cell.messageButton.hidden = false
    }

    return cell
}

Anybody have a solution to this problem?

Upvotes: 0

Views: 677

Answers (2)

Cristik
Cristik

Reputation: 32809

There are two possible solutions to your problem:

  1. Always set the hidden property:

    cell.messageButton.hidden = messages[indexPath.row] != ""

  2. Reset the state of your cell when it is reused, this provides deterministic behaviour in the table view controller, without burdening the controller class with tasks that a cell should do. This can be done by overwriting prepareForReuse in CathyTaskLogTableViewCell.

    func prepareForReuse() {
    super.prepareForReuse()
    self.messageButton.hidden = true // or false, depending on what's the initial state
    // other stuff that needs reset
}

With the current code, messageButton gets hidden only if the cell doesn't find something in messages. So for cells that had this button visible, were reused, and now correspond to a cell that doesn't have a correspondent in messages, the button will remain visible.

Upvotes: 0

iDhaval
iDhaval

Reputation: 3205

The reason for getting this result is because of UITableViewCell is being reuse.

if messages[indexPath.row] != "" {
    cell.messageButton.hidden = false
}
else
{
    cell.messageButton.hidden = true
}

Upvotes: 1

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