构造数组结构

- (NSMutableArray *)handleDataFrom:(NSArray *)arr{
    NSString *tempString = @"";
    for (NSDictionary *dic in arr) {
        NSMutableDictionary *elementDic = [NSMutableDictionary dictionary];
        NSMutableDictionary *tempDic = [NSMutableDictionary dictionary];
        NSString *firstLetter = [[dic objectForKey:@"firstLetter"] description];
        // 判断return的数组里是不是已经添加过当前遍历到的首字母
        if ([tempString isEqualToString:firstLetter]) {
            NSMutableDictionary *lastDic = [NSMutableDictionary dictionaryWithDictionary:[schoolArr_ lastObject]];
            NSMutableArray *valueArr = [NSMutableArray arrayWithArray:[lastDic objectForKey:firstLetter]];
            [tempDic setObject:[[dic objectForKey:@"id"] description] forKey:@"id"];
            [tempDic setObject:[[dic objectForKey:@"name"] description] forKey:@"name"];
            [valueArr addObject:tempDic];
            [elementDic setObject:valueArr forKey:firstLetter];
            [schoolArr_ removeLastObject];
        } else {
            [tempDic setObject:[[dic objectForKey:@"id"] description] forKey:@"id"];
            [tempDic setObject:[[dic objectForKey:@"name"] description] forKey:@"name"];
            [elementDic setObject:[NSMutableArray arrayWithObjects:tempDic, nil] forKey:firstLetter];
        }
        [schoolArr_ addObject:elementDic];
        tempString = firstLetter;
    }
    NSLog(@"%@",schoolArr_);

    return schoolArr_;
}

- (NSMutableArray *)handleDataFrom:(NSArray *)arr{
    NSString *tempString = @"";
//    NSMutableArray *resultArr = [[NSMutableArray alloc] init];
    for (NSDictionary *dic in arr) {
        NSMutableArray *elementArr = [NSMutableArray array];
        NSString *firstLetter = [[dic objectForKey:@"firstLetter"] description];
        // 判断return的数组里是不是已经添加过当前遍历到的首字母
        if ([tempString isEqualToString:firstLetter]) {
            elementArr = [NSMutableArray arrayWithArray:[schoolIdArr_ lastObject]];
            [elementArr addObject:[[dic objectForKey:@"id"] description]];
            [schoolIdArr_ removeLastObject];
        } else {
            [elementArr addObject:[[dic objectForKey:@"id"] description]];
        }
        [schoolIdArr_ addObject:elementArr];
        tempString = firstLetter;
    }
    return schoolIdArr_;
}