Question

I am trying to delete a row int the table view and after that saving the updated table view to an array in NSUserdefault. It looks like this:

 - (void)tableView:(UITableView *)tableView 

 commitEditingStyle:(UITableViewCellEditingStyle)editingStyle

  forRowAtIndexPath:(NSIndexPath *)indexPath {


NSMutableArray *stringsArray = [[NSUserDefaults standardUserDefaults] objectForKey:@"history"];
NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
NSMutableArray *history = [NSMutableArray arrayWithArray:[prefs objectForKey:@"history"]];    
 NSUInteger row = [indexPath row];

 NSUInteger count = [stringsArray count];


 if (row < count) {



    [stringsArray removeObjectAtIndex:row];


  [prefs setObject:history forKey:@"history"];
    [[NSUserDefaults standardUserDefaults] synchronize];
    [tableView reloadData]; 

    NSLog(@"tabort %d", row);
    NSLog(@"tabort %d", count);    
    NSLog(@"tabort %@", stringsArray);

    }

    }

When I run it I can delete one row but it does not get saved and when I try to delete the next row it craches with the following message:

2012-04-15 11:02:58.704 test220[88546:f803] * Terminating app due to
uncaught exception ‘NSInternalInconsistencyException’, reason:
‘-[__NSCFArray removeObjectAtIndex:]: mutating method sent to
immutable object’

What am I doing wrong?

Answer 1

Try changing the line:

NSMutableArray *stringsArray = [[NSUserDefaults standardUserDefaults] objectForKey:@"history"];

to:

NSMutableArray *stringsArray = [NSMutableArray arrayWithArray: [[NSUserDefaults standardUserDefaults] arrayForKey:@"history"]];