*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: '-[__NSCFArray insertObject:atIndex:]: mutating method sent to immutable object'
*** First throw call stack:
                commentArray = [[ NSMutableArray alloc ] init ];
            }
           
            NSArray *array = [responseObject objectForKey : @" comment " ];
           
            for ( int i= 0 ; i<array. count ; i++) {
               
                NSDictionary *dic = [array objectAtIndex :i];
                [ commentArray addObject :dic];
               
            }
           
            [ commentArray addObject : @"nihao" ];