Re: Profound UITableView rendering-performance problem, but only at certain positions?
Re: Profound UITableView rendering-performance problem, but only at certain positions?
- Subject: Re: Profound UITableView rendering-performance problem, but only at certain positions?
- From: Luke Hiesterman <email@hidden>
- Date: Mon, 23 Jul 2012 21:08:08 +0000
- Thread-topic: Profound UITableView rendering-performance problem, but only at certain positions?
On Jul 23, 2012, at 2:03 PM, Gavin Stokes wrote:
On Mon, Jul 23, 2012 at 8:16 AM, Fritz Anderson <email@hidden<mailto:email@hidden>>wrote:
I think the first problem you should concentrate on should be the
multiply-overlaid drawings. It's hard to tell what's going on unless you
share some code, or at least your design, so I can only ask general
questions.
Thanks for your response. The code is quite simple, so I'm happy to
provide it. But, because the occurrence of the problem depends entirely on
the existence of a partially exposed row in a previous section at the top
of the screen, I don't think any of this processing has anything to do with
the problem. There's only about a 50-pixel danger zone of scroll position
where it occurs, and that zone moves with row height, but not by any
discernible pattern.
I have Location Services set to give me heading updates every 10 degrees.
When my view controller gets called with a heading update, I do:
[self.stashTableView reloadRowsAtIndexPaths:[self.stashTableView
indexPathsForVisibleRows] withRowAnimation:UITableViewRowAnimationNone];
Though probably off topic, this is unnecessary work. If you just want to change where your arrow is pointing, you should reach into the cells and change the position of the arrow - you shouldn't be doing a reload for that. Think something more like for (UITableViewCell* cell in [tableView visibleCells]) {cell.thumbImageView.transform = TRANSFORM_CALCULATION;}
Luke
When the tableview calls me with willDisplayCell, and I do a bit of math to
combine the current heading with the angle toward a point of interest.
Then I tell the cell to rotate the arrow image, which is simply a
UIImageView:
CGAffineTransform rotation = CGAffineTransformMakeRotation(degrees * (M_PI
/ 180));
[self.thumbImageView setTransform:rotation];
That's it. Works great except for a very limited range of scroll offsets.
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