Shadow on UITableViewCell is giving bad performance

Question

I'm creating table view with custom cells, which looks like news feed - on gray background there are rectangles with rounded corners and shadow.

While cellForRowAtIndexPath method is calling I'm setting shadow like this:

cell.postCard.layer.cornerRadius = 3
cell.postCard.layer.shadowColor = UIColor.darkGrayColor().CGColor
cell.postCard.layer.shadowOffset = CGSizeMake(0,1)
cell.postCard.layer.shadowRadius = 3
cell.postCard.layer.shadowOpacity = 0.5
cell.layer.shadowPath = UIBezierPath(rect: cell.postCard.layer.bounds).CGPath

Where postCard is UIView - it's container for all context of cell.

I've read that I need to add shadowPath to get good performance but I think it's not working because when I'm slowly moving table view is stuttering. Can be reason of using simulator than real device?

Are you sure its the shadow and not the rounded corners? – dan Jan 15 '16 at 19:49 — dan, Jan 15 '16 at 19:49
Is it a way to improve setting corners? – Jan 15 '16 at 20:06 — , Jan 15 '16 at 20:06

score 1 · Accepted Answer · answered Jan 15 '16 at 19:45

1

You are setting shadow path to cell's layer, while modifying shadow settings for cell.postCard

cell.postCard.layer.shadowOpacity = 0.5
cell.layer.shadowPath = UIBezierPath(rect: cell.postCard.layer.bounds).CGPath

Is this really what you need?

answered Jan 15 '16 at 19:45

Shaman

61
5

Yeah, it wasn't my intention. Fortunately it improved performance, but the shadow is not correctly sized, I mean its smaller than postCard. – Jan 15 '16 at 20:05
You always can play with the shadow size in by increasing the rect. Use CGRectInset: rect = CGRectInset(rect, -increaseBy, -increaseBy) – Shaman Jan 15 '16 at 21:35
Height for the cells is dynamically creating. Some of the cells has shadow in a background in good size, I don't know why it's not woring – Jan 15 '16 at 21:50

score 0 · Answer 2 · answered Apr 10 '17 at 09:19

0

Also, you should set 'cell.clipsToBounds = false' for your cell.

answered Apr 10 '17 at 09:19

user2990759

127
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score 0 · Answer 3 · answered Apr 10 '17 at 09:27

0

Try to read about the shouldRasterize and how it is working with shadows and corner radius of the UI elements. You can boost performance by manipulation of the shouldRasterize value.

answered Apr 10 '17 at 09:27

Oleg Gordiichuk

15,240
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Shadow on UITableViewCell is giving bad performance

3 Answers3