Why doesn't my datasource property get set?

Question

I have a UITableView whose controller looks like this:

@interface FLWorkspaceViewController : UITableViewController

@property(nonatomic,retain) NSMutableArray* workspaces;

@end

I try to set that array in another controller:

for(NSDictionary* workspace in workspaces)
        {
            NSLog(@"%@",workspace);
            [workspaceViewController.workspaces addObject:workspace];
        }

        [self.navigationController pushViewController:workspaceViewController animated:YES];

I've checked the values and they exist. When I count workspaces in viewDidLoad, it's 0. Why is this?

make sure you have allocated memory to your workspaces array... — Ankit Srivastava, Jun 10 '12 at 08:43
please check that workspaceViewController & workspaceViewController.workspaces is not nil — Omar Abdelhafith, Jun 10 '12 at 08:43
possible duplicate of [Cannot add items to an NSMutableArray ivar](http://stackoverflow.com/questions/7125326/cannot-add-items-to-an-nsmutablearray-ivar), [NSMutableArray addObject: not affecting count](http://stackoverflow.com/questions/3683761/nsmutablearray-addobject-not-affecting-count), [NSMutableArray addObject: not working](http://stackoverflow.com/questions/1827058/nsmutablearray-addobject-not-working) — jscs, Jun 10 '12 at 18:21

Stefan · Accepted Answer · 2012-06-10T08:48:23.733

2

@property statements create the pointers for you, but not the actual content. Since I don't see it in your code: Do you alloc init your NSMutableArray *workspaces somewhere?

EDIT: Probably the best way to initialise your workspaces array would be in a getter method in the class where you define the @property. Lazy initialisation is preferrable. Best amend your @synthesize statement to read something like @synthesize workspaces = i_workspaces;, then you can write your getter like this:

- (NSMutableArray *)workspaces {
    if (i_workspaces == nil) {
        NSMutableArray *i_workspaces = [[NSMutableArray alloc] initWithCapacity:3];
    }
    return i_workspaces;
}

The capacity statement just helps the compiler optimise, it doesn't have to be exact.

edited Jun 10 '12 at 08:48

answered Jun 10 '12 at 08:37

Stefan

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you mean my NSMutableArray correct? I don't alloc init it anywhere. Should I do it in viewDidLoad? – Sheehan Alam Jun 10 '12 at 08:39
Probably the most solid solution would be to write a lazy-initialisation getter in `FLWorkspaceViewController`. I'll amend my answer in a second... – Stefan Jun 10 '12 at 08:40

Why doesn't my datasource property get set?

1 Answers1