TGRTimeline.m

- (void)loadTweetsWithRequest:(SLRequest *)request completionHandler:(void (^)(NSError *error))completionHandler
{
    self.loading = YES;
    
    [request performRequestWithHandler:^(NSData *responseData, NSHTTPURLResponse *urlResponse, NSError *error) {
        if (!error) {
            id response = [NSJSONSerialization JSONObjectWithData:responseData
                                                          options:0
                                                            error:NULL];
            
            if ([response isKindOfClass:[NSArray class]]) {
                [self.managedObjectContext performBlock:^{
                    [self importTweets:response];
                }];
            }
            else {
                NSLog(@"Error: %@", response[@"errors"][0][@"message"]);
            }
        }
        
        dispatch_async(dispatch_get_main_queue(), ^{
            self.loading = NO;
            completionHandler(error);
        });
    }];
}