ios: Updating UITableView inside AFNetworking success callback

Question

I'm trying to load data from API and show it inside a UITableView. I used AFNetworking for the network calls, but now I'm facing a problem: I can't access myTableView nor self inside the success block.

@property (weak, nonatomic) IBOutlet UITableView *myTableView; 
@property (nonatomic,retain) NSMutableArray *myDataSource;

@synthesize featuredProductsTableView;

- (void)viewDidLoad
{
    [super viewDidLoad];
    NetworkManager *networkManager = [NetworkManager  getInstance];
    myDataSource = [NSMutableArray array]; 

    [networkManager getPath:@"example.com" parameters:nil success:^(AFHTTPRequestOperation *operation, id JSON) {
        [myDataSource addObjectsFromArray:JSON];

        [myTableView reloadData]; 

    } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
        NSLog(@"%@",error);
    }];
}

Debugging the code shows that inside the block I can't access any of self, myDataSource, or myTableView.

How can I solve this issue?

Thanks.

To access myDataSource you should use __block myDataSource = [NSMutableArray array]; , self and myTableView must be accessable — B.S., Apr 25 '13 at 14:24
variables accessed inside a block without having being declared with __block prefix is a copy of the real variable — Jerome Diaz, Apr 25 '13 at 14:26
i changed it to @property (nonatomic,retain) __block NSMutableArray *myDataSource; and still can't access any of them — trrrrrrm, Apr 25 '13 at 14:35
Sorry where it is not accesable? Inside [networkManager getPath ... block ? — B.S., Apr 25 '13 at 14:37
when trying to add the JSON to the dataSource and reloading the tableView, debugging shows that self is 0x00000000 and the others are invalid Expressions — trrrrrrm, Apr 25 '13 at 14:41
@George ya some testing with __block fixed the problem, many thanks may you please add it as an answer so i can mark it. — trrrrrrm, Apr 25 '13 at 15:01

score 0 · Accepted Answer · edited May 23 '17 at 12:12

0

You should probably use :

__block myDataSource = [NSMutableArray array];

You can also read:

What does the "__block" keyword mean?

edited May 23 '17 at 12:12

Community

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answered Apr 25 '13 at 15:01

B.S.

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This is completely wrong. First, `__block` can only be applied to local variables. `myDataSource` is an instance variable. Second, even if it were a local variable, `__block` is only useful if the variable is assigned to. Nowhere is the variable assigned to other than when it is initialized before the block. – newacct Apr 25 '13 at 23:46
Read the question and comments before downvoting, as you see the question was edited – B.S. Apr 26 '13 at 06:48
`myDataSource` was an instance variable in the original version – newacct Apr 26 '13 at 07:03

score -2 · Answer 2 · edited May 23 '17 at 11:57

-2

Declare this right before your block:

__block typeof(self) this = self;

At least, this will allow you to reach self from inside the block, by calling it this.

Edit: that's not the way to go, my mistake. See How do I avoid capturing self in blocks when implementing an API?

edited May 23 '17 at 11:57

Community

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answered Apr 25 '13 at 14:45

Cyrille

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This is completely wrong. Of course you can access `self` from inside the block. – newacct Apr 25 '13 at 23:47
Then why does the static analyzer complain it's likely to lead to a retain cycle if I use `self` in (some) blocks? So I tried to teach myself and found this: http://stackoverflow.com/questions/7853915/how-do-i-avoid-capturing-self-in-blocks-when-implementing-an-api – Cyrille Apr 26 '13 at 06:46
it might lead to a retain cycle, but that does not mean you can't do it – newacct Apr 26 '13 at 07:03

ios: Updating UITableView inside AFNetworking success callback

2 Answers2