Dynamic cell height with async images in Swift 2

Question

I'm trying to build a Facebook-like feed. I'm using a standard Tableview with autolayout constraints set up in storyboard.

The width should be 100% of the viewport and the height according to the aspect ratio of the image.

I'm using Haneke's hnk_setImageFromURL for async image loading from the server.

I saw here the option to use tableview.beginUpdates() or endUpdates() and it causes the first render to work alright, but once I start scrolling the height calculation goes wrong, cells appear blank and/or the app crashes due to indexOutOfBounds.

Is manually calculating the height in heightForRowAtIndexPath with pre-given aspect ratio from the server the only option?

My relevant part of the code

ViewController:

func tableView(tableView: UITableView, estimatedHeightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
    return 500
}

func tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
    return UITableViewAutomaticDimension
}

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

      let cell = tableView.dequeueReusableCellWithIdentifier("FeedItem", forIndexPath: indexPath) as! FeedItemTableViewCell

      content.hnk_setImageFromURL(NSURL(string: contentImage)!, placeholder: nil, format: nil, failure: nil, success: {image in

                    cell.content.image = image  
                    self.beginUpdates()
                    self.endUpdates()

                }
        )
}

P.S. A side effect caused by using Haneke is that I have to provide some initial size to the UIImageView, currently I'm using a placeholder image which causes irritating animations when the image is loaded from the server

@BorjaCin I preloaded the aspect ratios for all images and used it in all calculations — Shahar, Dec 04 '17 at 09:19

score 0 · Answer 1 · edited Oct 09 '17 at 11:24

0

Here instead of loading cell data in the cellForRowAtIndex method,I have created a subclass of TableViewCell. And I have used SDWebImage instead of Haneke.

Hope this helps

edited Oct 09 '17 at 11:24

byJeevan

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answered Dec 03 '15 at 17:55

vivek takrani

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I didn't understand the part of subclassing TableViewCell (I didn't see any reference to it in the post). The thing is, if you're setting the constraint asynchronously, the scrolling is still jumpy and you still have to call beginUpdates() which animates the height. I'm trying to combine the solutions by saving the aspect ratio at the server side and applying the constraint synchronously. It's better than before but still a little jumpy. – Shahar Dec 03 '15 at 19:12

Dynamic cell height with async images in Swift 2

1 Answers1