NSMutableArray can't be added to
- by Dan Ray
I've had this sort of problem before, and it didn't get a satisfactory answer.
I have a viewcontroller with a property called "counties" that is an NSMutableArray. I'm going to drill down a navigation screen to a view that is about selecting the counties for a geographical search. So the search page drills down to the "select counties" page.
I pass NSMutableArray *counties to the second controller as I push the second one on the navigation stack. I actually set that second controller's "selectedCounties" property (also an NSMutableArray) with a pointer to my first controller's "counties", as you'll see below.
When I go to addObject to that, though, I get this:
*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: '*** -[NSCFArray insertObject:atIndex:]: mutating method sent to immutable object'
Here's my code:
in SearchViewController.h:
@interface SearchViewController : UIViewController
{
....
NSMutableArray *counties;
}
....
@property (nonatomic, retain) NSMutableArray *counties;
in SearchViewController.m:
- (void)getLocationsView
{
[keywordField resignFirstResponder];
SearchLocationsViewController *locationsController =
[[SearchLocationsViewController alloc] initWithNibName:@"SearchLocationsView" bundle:nil];
[self.navigationController pushViewController:locationsController animated:YES];
[locationsController setSelectedCounties:self.counties];
[locationsController release];
}
in SearchLocationsViewController.h:
@interface EventsSearchLocationsViewController : UIViewController
<UITableViewDelegate, UITableViewDataSource>
{
...
NSMutableArray *selectedCounties;
}
...
@property (nonatomic, retain) NSMutableArray *selectedCounties;
in SearchLocationsViewController.m (the point here is, we're toggling each element of a table being active or not in the list of selected counties):
-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
if ([self.selectedCounties containsObject:[self.counties objectAtIndex:indexPath.row]]) {
//we're deselcting!
[self.selectedCounties removeObject:[self.counties objectAtIndex:indexPath.row]];
cell.accessoryView = [[UIImageView alloc]
initWithImage:[UIImage imageNamed:@"red_check_inactive.png"]];
}
else {
[self.selectedCounties addObject:[self.counties objectAtIndex:indexPath.row]];
cell.accessoryView = [[UIImageView alloc]
initWithImage:[UIImage imageNamed:@"red_check_active.png"]];
}
[tableView deselectRowAtIndexPath:indexPath animated:YES];
}
We die at [self.selectedCounties addObject.... there.
Now, when I NSLog myself [self.selectedCounties class], it tells me it's an NSCFArray.
How does this happen? I understand about class bundles (or I THINK I do anyway), but this is explicitly a specific type, and it's losing it subclassing at some point in a way that kills the whole thing. I just completely don't understand why that would happen.
