在tableview单元格内单击时更改按钮

Question

I have a tableview cell and in every cell there is like button.

I want to make if the user clicks on the like button for the cell, it will change the button image.

This is my code:

func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCellWithIdentifier("Result", forIndexPath: indexPath) as! ResultTableViewCell
    cell.likebutton.tag = indexPath.row
    return cell
}

and the function

 @IBAction func printTag(sender: AnyObject) {
     let cell = tableView.dequeueReusableCellWithIdentifier("Result", forIndexPath: indexPath) as! ResultTableViewCell

     cell.likebutton.setImage(UIImage(named: "clicklike"), forState: UIControlState.Normal)
 }

Any fix?

Answer 1

You should never call dequeueReusableCellWithIdentifier from anywhere except cellForRowAtIndexPath . The flow is:

1. Like Button clicked
2. @IBAction handler fires as a result
3. handler looks up the tag number, updates the model to indicate it's in the 'like' state (the table's backing data -- where's your model? You may not understand how to create and manage one yet.)
4. handler calls table.reloadRowsAtIndexPaths() with the appropriate NSIndexPath
5. This propagates into iOS calling cellForRowAtIndexPath on your behalf which then needs to consult your model, notice that that particular row is in the 'liked' state, and render the image within the cell differently, before returning the cell.

This is probably a lot more than you thought, given your try above. How actionable is this for you now?

EDIT

I see you're still looking for shortcuts rather than modeling the data. You need something like:

// This is a data model. I'm not sure you understand how critical this is.
var isLikedAtIndex = [ false, false, false ] // Example only: array of 3 booleans

func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCellWithIdentifier("Result", forIndexPath: indexPath) as! ResultTableViewCell
    if isLikedAtIndex(indexPath.row) {
        cell.likebutton.setImage(someLikedImage)
    }
    else {
        cell.likebutton.setImage(someNotLikedImage)
    }
    cell.likebutton.tag = indexPath.row
    return cell
}


@IBAction func clickLike(sender: UIButton) {
    isLikedAtIndexPath(sender.tag) = true // !! The model !! Save your data!
    let myClickedIndexPath = NSIndexPath(forRow: sender.tag, inSection: 0)
    table.reloadRowsAtIndexPaths([myClickedIndexPath], withRowAnimation: .Automatic)
}

Answer 2

sender should be a reference to likebutton so you should be able to do the following:

sender.setImage(UIImage(named: "clicklike"), forState: UIControlState.Normal)

I think that you are going about this the wrong way though. When the cell is reused the likebutton will end up being in the wrong state for the new indexPath . The state of the likebutton should be determined in

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

or

tableView(tableView: UITableView, willDisplayCell cell: UITableViewCell, forRowAtIndexPath indexPath: NSIndexPath)

So, you shouldn't be dequeueing the cell in order to change the button like this. Rather, you should be changing the properties that determine the state of the button, and then calling reloadRowsAtIndexPaths(indexPaths: [NSIndexPath], withRowAnimation animation: UITableViewRowAnimation)

I'm not sure where you're getting the indexPath , but you can determine it using the sender like so:

let rootViewPoint = sender.superview?.convertPoint(sender.center, toView: self.tableView.center)
let indexPath = self.tableView.indexPathForRowAtPoint(rootViewPoint)

You can then use that indexPath in order to figure out which instance of your model needs to be changed, make the changes, and then call:

self.tableView.reloadRowsAtIndexPaths([indexPath], withRowAnimation: .Automatic)