App crash when I touch specific cell in UITableView - ios

Question

I have Maintableview(a UIViewController) with contents and detailview(a UIViewController) that show detail for each of cells in Maintableview.
I have added a "favorite" button in "detailview" that user can add to Favoritetableview(a UIViewController) and every thing work fine.
Now I have added "add to favorite" in Maintableview with swipe to left.
It adds contents successfully to Favoritetableview but when I touch that cell in Favoritetableview the app crashes.
Below is the console logs for the crash:
Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArrayI objectAtIndex:]: index 1 beyond bounds [0 .. 0]'
*** First throw call stack:
(
0 CoreFoundation 0x000000010a871d85 __exceptionPreprocess + 165
1 libobjc.A.dylib 0x000000010a2e3deb objc_exception_throw + 48
2 CoreFoundation 0x000000010a75a934 -[__NSArrayI objectAtIndex:] + 164
3 iranbirds 0x00000001075cf672 -[FavoriteTableViewController prepareForSegue:sender:] + 530
4 UIKit 0x00000001090c55d5 -[UIStoryboardSegueTemplate _performWithDestinationViewController:sender:] + 369
5 UIKit 0x00000001090c5433 -[UIStoryboardSegueTemplate _perform:] + 82
6 UIKit 0x0000000108b1b5f8 -[UIViewController performSegueWithIdentifier:sender:] + 99
7 iranbirds 0x00000001075cf42d -[FavoriteTableViewController tableView:didSelectRowAtIndexPath:] + 189
8 UIKit 0x0000000108ac51c6 -[UITableView _selectRowAtIndexPath:animated:scrollPosition:notifyDelegate:] + 1887
9 UIKit 0x0000000108ac541b -[UITableView _userSelectRowAtPendingSelectionIndexPath:] + 388
10 UIKit 0x0000000108989f62 _runAfterCACommitDeferredBlocks + 317
11 UIKit 0x000000010899de4c _cleanUpAfterCAFlushAndRunDeferredBlocks + 95
12 UIKit 0x00000001089aa147 _afterCACommitHandler + 90
13 CoreFoundation 0x000000010a796c37 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 23
14 CoreFoundation 0x000000010a796ba7 __CFRunLoopDoObservers + 391
15 CoreFoundation 0x000000010a78c7fb __CFRunLoopRun + 1147
16 CoreFoundation 0x000000010a78c0f8 CFRunLoopRunSpecific + 488
17 GraphicsServices 0x000000010be6bad2 GSEventRunModal + 161
18 UIKit 0x000000010897df09 UIApplicationMain + 171
19 iranbirds 0x00000001075d32ef main + 111
20 libdyld.dylib 0x000000010ba6492d start + 1
21 ??? 0x0000000000000001 0x0 + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
favorite table view:
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
NSIndexPath *indexPath = (NSIndexPath *)sender;
Favorite *fav = (Favorite *)[self.fetchedResultsController objectAtIndexPath:indexPath];
NSString *combinedName = fav.name;
if ([segue.identifier isEqualToString:#"FavoriteBirdDetail"])
{
GeneralViewController *detailViewController = (GeneralViewController*)[segue destinationViewController];
detailViewController.birdName = [combinedName componentsSeparatedByString:#"^"][0];;
detailViewController.sciName = [combinedName componentsSeparatedByString:#"^"][1];;
detailViewController.managedOjbectContext = self.managedOjbectContext;
}
}
This line cause error:
detailViewController.sciName = [combinedName componentsSeparatedByString:#"^"][1];
Any help would be appreciated.

Answer 1

detailViewController.sciName = [combinedName componentsSeparatedByString:#"^"][1];
Well, look at this code - you are getting second object from an array by subscript syntax. And the code would work if an array contains at least 2 items.
It looks like your array contains zero or one element, that is why app crashes when you try to get an element by 1 index - [1], which means the second element.
To prevent crash you should check an array count property before:
NSArray *anArray = [combinedName componentsSeparatedByString:#"^"];
if anArray.count >= 2 {
detailViewController.sciName = anArray[1];
}