Are AFNetworking success/failure blocks invoked on the main thread?

Question

Does AFNetworking call the completion block on the main thread? or is it called in the background, requiring me to manually dispatch my UI updates to the main thread?

Using code instead of words, this is the example code from the AFNetworking documentation with the call to NSLog replaced by a UI update:

AFJSONRequestOperation *operation = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
    self.label.text = JSON[@"text"];
} failure:nil];

Should it be written like this instead?

AFJSONRequestOperation *operation = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
    dispatch_async(dispatch_get_main_queue(), ^{
        self.label.text = JSON[@"text"];
    });
} failure:nil];

Answer 1

They are invoked on the main queue, unless you explictly sets the queue on AFHTTPRequestOperation, as shown in setCompletionBlockWithSuccess:failure from AFHTTPRequestOperation.m

self.completionBlock = ^{
    if (self.error) {
        if (failure) {
            dispatch_async(self.failureCallbackQueue ?: dispatch_get_main_queue(), ^{
                failure(self, self.error);
            });
        }
    } else {
        if (success) {
            dispatch_async(self.successCallbackQueue ?: dispatch_get_main_queue(), ^{
                success(self, self.responseData);
            });
        }
    }
};