gistfile1.m

-(void) addNewItemFromArray:(NSArray *) newArrItem
{
        // Add
        [_arrPhotos addObjectsFromArray:newArrItem];
        
        NSMutableArray *arrNewIndexpath = [NSMutableArray array];
        for (NSInteger i = _arrPhotos.count ; i < _arrPhotos.count +  newArrItem.count ; i++)
        {
                NSIndexPath *newIndexPath = [NSIndexPath indexPathForRow:i inSection:0];
                [arrNewIndexpath addObject:newIndexPath];
        }
        
        // Add new item with animation
        [_collectionView performBatchUpdates:^{
                                 [_collectionView insertItemsAtIndexPaths:arrNewIndexpath];
                             } completion:^(BOOL finished) {
                                 
                             }];
}