Crash on Device but not in Simulator when deleteRowsAtIndexPaths

Question

Hi,
I'm getting this crash:
* Assertion failure in -[UITableView _endCellAnimationsWithContext:], /SourceCache/UIKit/UIKit-963.10/UITableView.m:729
2009-08-26 11:30:28.718 xxx[494:5917] * Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Invalid update: invalid number of rows in section 0. The number of rows contained in an existing section after the update (7) must be equal to the number of rows contained in that section before the update (8), plus or minus the number of rows inserted or deleted from that section (0 inserted, 2 deleted).'
When calling this:
[self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObjects:indexPath] withRowAnimation:UITableViewRowAnimationFade];
Not really sure what's going on. This works in the simulator no problem. I have no idea why it says 2 deleted since indexPath is declared like this:
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:(int)[sender tag] inSection:0];
So it can really only be one row that's being deleted.
Have any of you guys experienced this before? I'm lost on this one.
-Thanks

Answer 1

Hi Matt, and welcome to the Dev Forum!
[self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObjects:indexPath]];
arrayWithObjects requires a nil terminated list. You could just strip the 's' off of Objects in this case, or add the terminator:
// this:
[NSArray arrayWithObject:indexPath]
// or this:
[NSArray arrayWithObjects:indexPath, nil]
When a required terminator is missing, the result is generally unpredictable. For example, your simulator binary might've wound up with 4 zero bytes after indexPath, while the device binary did not. This crash is an excellent example of how easily we can draw the wrong conclusion when comparing simulator and device runs. Note also, that if the code surrounding the above were changed in any way, you might be able to get the simulator to crash as well. Yet another way these machines know how to make people crazy.
Hope that helps!
- Ray