如何按字典键过滤字典数组答案

【问题标题】：How do I filter array of dictionaries by dictionary key如何按字典键过滤字典数组
【发布时间】：2014-07-19 10:55:17
【问题描述】：

这是我的 JSON。这是总共 250 个国家/地区，我在下面仅列出了 3 个。在这里我需要做的事情是我将国家解析为基于大陆的七个不同的数组。

{
  "geonames" : [
    {
      "languages" : "ca",
      "east" : 1.786542777831983,
      "continent" : "EU",
      "geonameId" : 3041565,
      "population" : "84000",
      "areaInSqKm" : "468.0",
      "countryName" : "Andorra",
      "south" : 42.42849259876837,
      "countryCode" : "AD",
      "capital" : "Andorra la Vella",
      "isoAlpha3" : "AND",
      "fipsCode" : "AN",
      "isoNumeric" : "020",
      "west" : 1.407186714111276,
      "continentName" : "Europe",
      "north" : 42.65604389629997,
      "currencyCode" : "EUR"
    },
    {
      "languages" : "ar-AE,fa,en,hi,ur",
      "east" : 56.38166046142578,
      "continent" : "AS",
      "geonameId" : 290557,
      "population" : "4975593",
      "areaInSqKm" : "82880.0",
      "countryName" : "United Arab Emirates",
      "south" : 22.63332939147949,
      "countryCode" : "AE",
      "capital" : "Abu Dhabi",
      "isoAlpha3" : "ARE",
      "fipsCode" : "AE",
      "isoNumeric" : "784",
      "west" : 51.58332824707031,
      "continentName" : "Asia",
      "north" : 26.08415985107422,
      "currencyCode" : "AED"
    },
    {
      "languages" : "fa-AF,ps,uz-AF,tk",
      "east" : 74.879448,
      "continent" : "AS",
      "geonameId" : 1149361,
      "population" : "29121286",
      "areaInSqKm" : "647500.0",
      "countryName" : "Afghanistan",
      "south" : 29.377472,
      "countryCode" : "AF",
      "capital" : "Kabul",
      "isoAlpha3" : "AFG",
      "fipsCode" : "AF",
      "isoNumeric" : "004",
      "west" : 60.478443,
      "continentName" : "Asia",
      "north" : 38.483418,
      "currencyCode" : "AFN"
    }
  ]
}

【问题讨论】：

第 1 步：将 JSON 解析为 NSDictionary with the NSData` 方法 JSONObjectWithData。第 2 步：尝试弄清楚如何按大陆创建七个数组。编写您的代码，如果有问题发布代码并寻求帮助。

标签： ios objective-c json ios7

【解决方案1】：

这是您可以过滤geonames 数组的方法。方法filterArrayByADictionary 获取一个数组和搜索条件，并返回过滤后的字典数组。

-(NSArray *)filterArrayByADictionary:(NSArray *)aArray andKey:(NSString *)aPredicte
{
    NSPredicate *filter = [NSPredicate predicateWithFormat:aPredicte];
    return [aArray filteredArrayUsingPredicate:filter];
}

你可以像这样调用这个方法。

NSArray *AsiaCounties =  [self filterArrayByADictionary: geonames andKey:@"continent = 'AS'"];
NSArray *EuropeCounties =  [self filterArrayByADictionary: geonames andKey:@"continent = 'EU'"];
// rest of the continents...

【讨论】：

【解决方案2】：

假设您在NSDictionary 中获取了此输出：

NSDictionary *mainDic;

NSMutableArray *arr = [NSMutableArray new];
NSMutableArray *arrcontinent1 = [NSMutableArray new];
NSMutableArray *arrcontinent2 = [NSMutableArray new];

arr = [mainDic valueForKey:@"geonames"];

for(int i=0; i<[arr count];i++){
    NSDictionary *dic = [arr objectAtIndex:i];
    if([[dic valueForKey:@"continent"] isEqualToString:@"EU"]){
        [arrcontinent1 addObject:dic];
    }
    else if([[dic valueForKey:@"continent"] isEqualToString:@"AS"]){
        [arrcontinent2 addObject:dic];
    }
//        and so on......
}

【讨论】：