Image block inside table view cell and change autolayout

Question

I have a cell which contains 2 multi-lines labels and an UIImageView. Cell has a dynamic height and it's calculated automatically using Autolayout. My problem is that I download an image in cellForRowAtIndexPath: and until then I don't know the height of the image. At the beginning the cell doesn't has the correct layout, I have to scroll to other cells and when I go back to my cell (it re-draws) then layout is correct. How can I re-draw the cell when the image is downloaded? Here's the code I'm using:

NSString static * cellIdentifier = @"titlePostCell";

PostTitleTableViewCell * cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier];

if (!cell) {
    cell = [[PostTitleTableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier];
}

cell.titleLabel.text = self.entry.title;
cell.descriptionLabel.text = self.entry.entry_description[@"value"];

[cell setNeedsUpdateConstraints];


[cell.postImageView pin_setImageFromURL:[[CTImageHelper sharedInstance] resizedImageURLConverterFromStringWithPrefix:self.entry.card_image] completion:^(PINRemoteImageManagerResult *result) {

    cell.heightSize = [NSNumber numberWithInt:result.image.size.height/2];
    cell.heightImageConstraint.constant = cell.heightSize.floatValue;

}];

return cell;

Thanks!

You need to make autolayout of cell such that cell's height should be having dependency of uiimageview height. I don't think giving constraints in cellForRowIndex within block is good way. — nikhil84
@nikhil84 cell depends on image size and both labels, as they are multilines and they dont have a fixed size — Joan Cardona

Eric Galluzzo Eric Galluzzo · Accepted Answer · 2016-01-14T13:04:22

If you have a pointer to the cell (e.g. in your block), you can accomplish this via the following code:

NSIndexPath *indexPath = [tableView indexPathForCell:cell];
[tableView reloadRowsAtIndexPaths:@[indexPath]];

However, I would argue that in general, resizing table view cells without the user specifically requesting you to do so is a poor UI practice. Imagine the UI jumping around on a user as they're trying to use it! Instead, I would use a fixed size for your UIImageViews in your cells. You can place an image of any size into such an image view by setting its contentMode to UIViewContentModeScaleAspectFit.

Image block inside table view cell and change autolayout

1 Answers