Stop Tableview from crashing when array is empty? - iphone

Question

At first my table view is empty, and then you can add your own cells to it. When you delete those cells, everything works fine. However, if you delete the last cell, then my NSMutableArray has no objects in it, and I get this error in my console (also, I'm using Core Data to save the cells):
*** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[_PFBatchFaultingArray objectAtIndex:]: index (123150308) beyond bounds (1)'
I also tried putting in this line of code, but I still get the same results:
//arr is my mutable array
if ([arr count] == 0) {
NSLog(#"No Cells");
}
This is how I delete an object from the table view:
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
if (editingStyle == UITableViewCellEditingStyleDelete) {
[arr removeObjectAtIndex:0];
[context deleteObject:[arr objectAtIndex:0]];
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
}
}
How would I solve this problem?

Answer 1

Ok.
There are two problems I have found in you code.
1- Why you are removing every time object at Index 0 ?
2- After removing an object from array[arr removeObjectAtIndex:0]; than from the same array of index you are passing an object to core Data to delete it
[context deleteObject:[arr objectAtIndex:0]];
This might be the problem.
This will surely help you.
Use this:
[context deleteObject:[arr objectAtIndex:indexPath.row]];
[arr removeObjectAtIndex:indexPath.row];
Thanks :)

Answer 2

If you look at the error message, the reason your code is failing is because some of your code is looking for a nonexistent index of 123150308. Without seeing your full code, it is impossible what exactly is wrong, but there is a simple fix.
A good way to solve the issue of an exception in code where the exception is "expected behavior" is to use #try blocks. This is your tableView method with #try blocks in place:
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
if (editingStyle == UITableViewCellEditingStyleDelete) {
#try {
[arr removeObjectAtIndex:0];
[context deleteObject:[arr objectAtIndex:0]];
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
}
#catch (NSRangeException *exception) {
// Something was out of range; put your code to handle this case here
}
}
}
However, without the context of the rest of your app, it is impossible to tell if this is the error. If you try this and it doesn't work, then the error is deeper in your application