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Usually, Xcode shows a warning when using a strong reference in a block (retain cycle). However, I don't understand why it doesn't show it with this AFNetworking example. 

UIImageView *imageView;
AFHTTPRequestOperation *operation = [apiQueryManager HTTPRequestOperationWithRequest:request success:^(AFHTTPRequestOperation *operation, NSData *responseObject) {
     UIImage *image = [UIImage imageWithData:responseObject];
     imageView.image =image;  // <--- using strong ref to imageView ?
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
     NSLog(@"ERROR: %@", error);
}];
[apiQueryManager enqueueHTTPRequestOperation:operation];

Is there a retain cycle here?

Amar
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Noé Malzieu
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1 Answers1

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To have a retain cycle because of imageView, imageView would need to have a strong reference to the block in which it is used. This is not the case.

jbat100
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    In your example, Noe, a retain cycle would occur if `operation` is used within the block. – Guy Kogus Nov 15 '13 at 10:08
  • Ok I get it now :) Thank you both And by the way, I think AFNetworking gives the parameters of the success block as weak references (if I'm not mistaken), so, @GuyKogus, there would be no retain cycle ? – Noé Malzieu Nov 15 '13 at 10:12
  • A retain cycle often occurs when an object retains a block which retains that object (sounds confusing, I know). When you call a block, the parameters being passed into it are not retained in the block object (yes, blocks are objects), so there's no retain cycle. – Guy Kogus Nov 15 '13 at 10:27