cellForRowAtIndexPath NSRangeException - ios

Question

Application Specific Information:
*** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -'[__NSArrayM objectAtIndex:]: index 5 beyond bounds [0 .. 3]'
0 CoreFoundation __exceptionPreprocess + 124
1 libobjc.A.dylib objc_exception_throw + 56
2 CoreFoundation -[__NSArrayM removeObjectAtIndex:] + 0
3 UIKit -[UITableView cellForRowAtIndexPath:] + 252
4 someApp -[businessViewClass methodA:] (businessViewClass.m:298)
5 someApp -[businessViewClass scrollViewDidScroll:] (businessViewClass.m:292)
6 UIKit -[UIScrollView(UIScrollViewInternal) _notifyDidScroll] + 76
7 UIKit -[UIScrollView setContentOffset:] + 460
8 UIKit -[UITableView setContentOffset:] + 300
9 UIKit -[UIScrollView(UIScrollViewInternal) _adjustContentOffsetIfNecessary] + 60
10 UIKit -[UIScrollView setContentSize:] + 128
11 UIKit -[UITableView _applyContentSizeDeltaForEstimatedHeightAdjustments:] + 56
12 UIKit -[UITableViewRowData setHeight:forRowAtIndexPath:] + 572
13 UIKit __53-[UITableView _configureCellForDisplay:forIndexPath:]_block_invoke + 3016
14 UIKit +[UIView(Animation) performWithoutAnimation:] + 80
15 UIKit -[UITableView _configureCellForDisplay:forIndexPath:] + 460
16 UIKit -[UITableView _createPreparedCellForGlobalRow:withIndexPath:willDisplay:] + 788
17 UIKit -[UITableView _createPreparedCellForGlobalRow:willDisplay:] + 80
18 UIKit -[UITableView _updateVisibleCellsNow:isRecursive:] + 2360
19 UIKit -[UITableView cellForRowAtIndexPath:] + 136
20 someApp -[businessViewClass methodA:] (businessViewClass.m:298)
21 UIKit -[UIScrollView(UIScrollViewInternal) _notifyDidScroll] + 76
22 UIKit -[UIScrollView setContentOffset:] + 460
23 UIKit -[UITableView setContentOffset:] + 300
24 UIKit -[UIScrollView _smoothScrollWithUpdateTime:] + 2400
25 QuartzCore CA::Display::DisplayLinkItem::dispatch() + 40
26 QuartzCore CA::Display::DisplayLink::dispatch_items(unsigned long long, unsigned long long, unsigned long long) + 424
27 IOKit 0x000000018334de54 0x183348000 + 24148
28 CoreFoundation __CFMachPortPerform + 180
29 CoreFoundation __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 56
30 CoreFoundation __CFRunLoopDoSource1 + 436
31 CoreFoundation __CFRunLoopRun + 1800
32 CoreFoundation CFRunLoopRunSpecific + 384
33 GraphicsServices GSEventRunModal + 180
34 UIKit UIApplicationMain + 204
35 someApp main (main.m:15)
36 libdyld.dylib 0x0000000182b528b8 0x182b50000 + 10424
This is what happend.
I find an bug that exists in app online, but I can't reproduce it with project code. It seems a business method was called when scroll the UIScrollview, and this business method call cellForRowAtIndexPath method of UITableView, and then cellForRowAtIndexPath trigs the scrollViewDidScroll method of UIScrollView. And I call cellForRowAtIndexPath in scrollViewDiddScroll method. It comes back. but It doesn't recurrence because next method called is NSArrayM removeObjectAtIndex instead of trigging the ScrollViewDidScroll method of UIScrollView. and then NSRangeException occurred.
is there anybody meet this or any ideas? thank you.

Answer 1

Your numberOfRowsInSection method of tableview is returns value that is greater than your array of count.
array's count is 3 and you are accessing 5th object of array.

Answer 2

What you can do is put a check to avoid any such crash, just look at this example code. This will be helpful just in case you aren't able to reproduce it.
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return self.yourArray.count;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier];
if (self.yourArray.count > indexPath.row)
{
// your code for the cell
}
return cell;
}

Answer 3

Your counting through an array but you are counting too far, thus not in bounds. You need to count the exact amount of units in the array.
Use this:
[_array count];