有一个数组,数组中有13个元素,先将该数组进行分组,每3个元素为一组,分为若干组,最后用一个数组统一管理这些分组.(要动态创建数组)

NSArray *arr = [NSArray arrayWithObjects:@1, @2, @3, @4, @5, @6, @7, @8, @9, @10, @11, @12, @13, nil];        NSUInteger numOfTeam = 0;        //计算分组个数        if ([arr count] % 3 == 0) {            numOfTeam = [arr count] / 3;        } else {            numOfTeam = [arr count] / 3 + 1;        }        //定义可变字典        NSMutableDictionary *dic = nil;        //定义可变数组        NSMutableArray *manageArr = [NSMutableArray arrayWithCapacity:numOfTeam];        //定义无符号整数集合        NSIndexSet *indexSet = nil;        //把每组的元素放在manageArr中        for (NSUInteger i = 0; i < numOfTeam; i++) {            if (i == [arr count] / 3) {                //若分配到最后一组,则为最后一组分配[arr count] % 3的length                indexSet = [[NSIndexSet alloc] initWithIndexesInRange:NSMakeRange(i * 3, [arr count] % 3)];            } else {                ////若不到最后一组,则分配3的length                indexSet = [[NSIndexSet alloc] initWithIndexesInRange:NSMakeRange(i * 3, 3)];            }            //将3个元素放在temp数组中            NSArray *temp = [NSArray arrayWithArray:[arr objectsAtIndexes:indexSet]];            //制作字典dic的key为str            NSString *str = [NSString stringWithFormat:@"%lu", i];            dic = [NSMutableDictionary dictionaryWithObject:temp forKey:str];            [manageArr addObject:[dic objectForKey:str]];        }        NSLog(@"manageArr:%@", manageArr);