从网络上下载省份城市名称并存入文件然后进行读取省份城市

//实现的功能是 从后台拿到城市的省份以及名称，然后保存在本地的沙盒中 在使用的时候再拿出来用。

步骤1

//向后台请求数据

 //忽略缓存
    [RequestTools postJSONWithUrl:G.YB_GetZoneList parameters:@{} success:^(id responseObject) {
        NSError *error = nil;
        NSDictionary *dic = [NSJSONSerialization JSONObjectWithData:responseObject options:NSJSONReadingAllowFragments error:&error];
        if (error) {
            NSLog(@"json error:%@",error);
        } else {
            if (![dic[@"code"] isEqualToString:@"GOOD"]) {
                return;
            }
            if (![[dic objectForKey:@"content"] isKindOfClass:[NSNull class]]) {
                //对数据进行解析
                NSArray *provinces = [dic objectForKey:@"content"];
                if (provinces.count > 0) {
                    //重要代码
                    [[AccountManager shareManager] cacheCitiesInfomation:provinces];
                    _locationArray = [[AccountManager shareManager] getCitiesInfomation];
                }
            }
            
        }
        
    } fail:^(id obj) {
        NSLog(@"error:%@",obj);
    }];

 步骤二：将解析到到的数据存起来

///缓存地区信息
- (void)cacheCitiesInfomation:(NSArray *)provincesDic{
    NSString *citiesPath = [self getPathWithFileName:@"cities.data"];
    [provincesDic writeToFile:citiesPath atomically:YES];
}

- (NSString *)getPathWithFileName:(NSString *)fileName{
    NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
    return [path stringByAppendingPathComponent:fileName];
}

 步骤三：从文件中读取信息

///读取地区信息
- (NSArray *)getCitiesInfomation{
    NSString *citiesPath = [self getPathWithFileName:@"cities.data"];
    NSArray *provincesDic = [[NSArray alloc] initWithContentsOfFile:citiesPath];
    if (provincesDic==nil || provincesDic.count==0) {
        return nil;
    }
    NSMutableArray *provinces = [NSMutableArray array];
    for (NSDictionary *proDic in provincesDic) {
        FCZoneProvince *province = [[FCZoneProvince alloc] init];
        province.provinceName = proDic[@"provinceName"];
        //某一省下的所有市
        NSArray *citiesDic = proDic[@"cities"];
        NSMutableArray *cities = [NSMutableArray array];
        for (NSDictionary *cityDic in citiesDic) {
            FCZoneCity *city = [[FCZoneCity alloc] init];
            city.cityName = cityDic[@"cityName"];
            //某一城市下的所有区
            NSArray *countriesDic = cityDic[@"counties"];
            NSMutableArray *coutries = [NSMutableArray array];
            for (NSDictionary *countryDic in countriesDic) {
                FCZoneCountry *country = [[FCZoneCountry alloc] init];
                country.countryName = countryDic[@"countyName"];
                if ([country.countryName isEqualToString:@"市辖区"]) {
                    continue;
                }
                [coutries addObject:country];
            }
            city.countries = coutries;
            [cities addObject:city];
        }
        province.cities = cities;
        [provinces addObject:province];
    }
    return provinces;
}

 这样就获得了    provinces  and  cities

 在这里我只是提供一个这样的思路，有了思路估计很快就可以上手了吧。