Swapnil Dhanwal Swapnil Dhanwal - 1 year ago 178
Swift Question

Shadow not conforming to the shape of view in UITableViewCell

I have a table view in which I'm trying to add card-style cells. To achieve this, I added a UIView (paddingView) onto the cell's content view, sized slightly smaller than it. Now to create the shadow effect, I am using the following code:

let path = UIBezierPath(rect: cell.paddingView.bounds)
cell.paddingView.layer.shadowPath = path.CGPath
cell.paddingView.layer.shadowOffset = CGSizeMake(0.5, 0.5)
cell.paddingView.layer.shadowOpacity = 0.4

The problem arises when the table view is first loaded. The shadow under each cell appears as follows:

enter image description here

This is how it looks when I scroll it once
How can I ensure that the shadow effect is proper, and not like the above image?

enter image description here

Answer Source

The wrong shadow width issue that you are seeing at first load is related to using the bounds of the paddingView before the cell's subviews are laid out.

When a cell is instantiated, it can start out with the wrong initial width (which is based on the storyboard), instead of being initially set to the actual width of the tableView.

The reason why the issue goes away after scrolling off- then on-screen is that the reused cell has the right paddingView bounds width, so the shadow now appears correct.

This was a common issue for self-sizing cells not initially being laid out properly, until the table was (scrolled or) reloaded. There are several workarounds going back almost two years, that vary from reloading the table, to forcing a layout pass.

Both ensure that the cell initial width is correct at first use.

If you're supporting older versions of iOS, this issue can crop up. I don't recall which exact version of iOS fixed it for good, but I haven't had to work around this issue in quite a while.

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