iOS: Twitter Paging adding more Tweets

I am attempting to add Pagination to my Twitter Client on iOS using AFNetworking. However when I run the method to get the tweets I get this error:

2015-02-01 15:39:47.428 Floadt[49165:2116574] CRASH :
 -[__NSCFArray insertObject:atIndex:]: mutating method sent to immutable object
2015-02-01 15:39:47.429 Floadt[49165:2116574] STACK TRACE :
 (
    0   CoreFoundation                      0x00000001101f2f35 __exceptionPreprocess + 165
    1   libobjc.A.dylib                     0x000000010fe8bbb7 objc_exception_throw + 45
    2   CoreFoundation                      0x00000001101f2e6d +[NSException raise:format:] + 205
    3   CoreFoundation                      0x00000001101eb6ea -[__NSCFArray insertObject:atIndex:] + 106
    4   CoreFoundation                      0x0000000110117a43 -[NSMutableArray insertObjects:count:atIndex:] + 179
    5   CoreFoundation                      0x0000000110117774 -[NSMutableArray insertObjectsFromArray:range:atIndex:] + 372
    6   CoreFoundation                      0x0000000110117574 -[NSMutableArray addObjectsFromArray:] + 612
    7   Floadt                              0x000000010cadc9ac __57-[TwitterTableViewController fetchNextTwitterPageWithID:]_block_invoke + 188
    8   Floadt                              0x000000010cabdcc3 __64-[AFJSONRequestOperation setCompletionBlockWithSuccess:failure:]_block_invoke91 + 51
    9   libdispatch.dylib                   0x000000011234cba6 _dispatch_call_block_and_release + 12
    10  libdispatch.dylib                   0x000000011236a7f4 _dispatch_client_callout + 8
    11  libdispatch.dylib                   0x00000001123538fb _dispatch_main_queue_callback_4CF + 949
    12  CoreFoundation                      0x000000011015afe9 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 9
    13  CoreFoundation                      0x000000011011deeb __CFRunLoopRun + 2043
    14  CoreFoundation                      0x000000011011d486 CFRunLoopRunSpecific + 470
    15  GraphicsServices                    0x0000000111b7a9f0 GSEventRunModal + 161
    16  UIKit                               0x000000010ebd3420 UIApplicationMain + 1282
    17  Floadt                              0x000000010cb30ed3 main + 115
    18  libdyld.dylib                       0x000000011239f145 start + 1
    19  ???                                 0x0000000000000001 0x0 + 1
)

Here is my method to get the older tweets:

-(void)fetchNextTwitterPageWithID:(NSString *)objectID {
    self.twitterClient = [[AFOAuth1Client alloc] initWithBaseURL:[NSURL URLWithString:@"http://ift.tt/YFagLh"] key:@"XXXXXX" secret:@"XXXXXX"];

    NSDictionary *parameters = @{
                                 @"max_id" :objectID
                                 };

    AFOAuth1Token *twitterToken = [AFOAuth1Token retrieveCredentialWithIdentifier:@"TwitterToken"];
    [self.twitterClient setAccessToken:twitterToken];
    [self.twitterClient registerHTTPOperationClass:[AFJSONRequestOperation class]];
    [self.twitterClient getPath:@"statuses/home_timeline.json" parameters:parameters success:^(AFHTTPRequestOperation *operation, id responseObject) {
        NSMutableArray *responseArray = (NSMutableArray *)responseObject;
        //NSLog(@"Response: %@", responseObject);
        tweets = [tweets copy];
        [tweets addObjectsFromArray:responseArray];
        [self.tableView reloadData];
    } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
        NSLog(@"Error: %@", error);
    }];
}

Here is my method to detect that the User reached the bottom of the table view (this works perfectly fine):

-(void) tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
{
    if ([tweets count] == (indexPath.row+1)) {
        NSDictionary *totalArray = tweets[indexPath.row];
        NSString *cellID = [totalArray objectForKey:@"id"];
        NSLog(@"%@",cellID);
        [self fetchNextTwitterPageWithID:cellID];
    }
}