ios - Swift-在JSON文件中搜索特定值并在同一数组中获取整个字典数组

Question

这有点令人费解，但是我有一个包含邮政编码和城市数据的JSON文件，其格式如下:

[{
    "zip_code" : 32071,
    "latitude" : 30.036193,
    "longitude" : -82.932228,
    "city" : "O Brien",
    "state" : "FL",
    "county" : "Suwannee"
  },
  {
    "zip_code" : 32072,
    "latitude" : 30.36036,
    "longitude" : -82.25418,
    "city" : "Olustee",
    "state" : "FL",
    "county" : "Baker"
  },
  {
    "zip_code" : 32073,
    "latitude" : 30.119884,
    "longitude" : -81.791546,
    "city" : "Orange Park",
    "state" : "FL",
    "county" : "Clay"
  },
  {
    "zip_code" : 32079,
    "latitude" : 29.984882,
    "longitude" : -81.802221,
    "city" : "Penney Farms",
    "state" : "FL",
    "county" : "Clay"
  },
  {
    "zip_code" : 32080,
    "latitude" : "",
    "longitude" : "",
    "city" : "Saint Augustine",
    "state" : "FL",
    "county" : "Saint Johns"
  },
  {
    "zip_code" : 46929,
    "latitude" : 40.556269,
    "longitude" : -86.490521,
    "city" : "Flora",
    "state" : "IN",
    "county" : "Carroll"
  }]

我想在我的应用程序中执行的操作是给它提供一个邮政编码，然后从包含该邮政编码的数组中返回数据。因此，如果我正在寻找 32071，它将在对象中返回 zip， latitude， longitude等，然后可以通过 object.city或 object.county引用它。
尝试使用 getIndex(for:)进行此操作，但是没有用。我能够成功打印解码后的数据，只是无法进行下一步工作。
编辑:这是我的解码器:

struct City: Codable {
    let zipCode: Int
    let latitude, longitude: Itude
    let city: String
    let state: State
    let county: String

    enum CodingKeys: String, CodingKey {
        case zipCode = "zip_code"
        case latitude, longitude, city, state, county
    }
}

enum Itude: Codable {
    case double(Double)
    case string(String)

    init(from decoder: Decoder) throws {
        let container = try decoder.singleValueContainer()
        if let x = try? container.decode(Double.self) {
            self = .double(x)
            return
        }
        if let x = try? container.decode(String.self) {
            self = .string(x)
            return
        }
        throw DecodingError.typeMismatch(Itude.self, DecodingError.Context(codingPath: decoder.codingPath, debugDescription: "Wrong type for Itude"))
    }

    func encode(to encoder: Encoder) throws {
        var container = encoder.singleValueContainer()
        switch self {
        case .double(let x):
            try container.encode(x)
        case .string(let x):
            try container.encode(x)
        }
    }
}

enum State: String, Codable {
    case aa = "AA"
    case ae = "AE"
    case ak = "AK"
    case al = "AL"
    case ap = "AP"
    case ar = "AR"
    case az = "AZ"
    case ca = "CA"
    case co = "CO"
    case ct = "CT"
    case dc = "DC"
    case de = "DE"
    case fl = "FL"
    case fm = "FM"
    case ga = "GA"
    case gu = "GU"
    case hi = "HI"
    case ia = "IA"
    case id = "ID"
    case il = "IL"
    case ks = "KS"
    case ky = "KY"
    case la = "LA"
    case ma = "MA"
    case md = "MD"
    case me = "ME"
    case mh = "MH"
    case mi = "MI"
    case mn = "MN"
    case mo = "MO"
    case mp = "MP"
    case ms = "MS"
    case mt = "MT"
    case nc = "NC"
    case nd = "ND"
    case ne = "NE"
    case nh = "NH"
    case nj = "NJ"
    case nm = "NM"
    case nv = "NV"
    case ny = "NY"
    case oh = "OH"
    case ok = "OK"
    case or = "OR"
    case pa = "PA"
    case pr = "PR"
    case pw = "PW"
    case ri = "RI"
    case sc = "SC"
    case sd = "SD"
    case stateAS = "AS"
    case stateIN = "IN"
    case tn = "TN"
    case tx = "TX"
    case ut = "UT"
    case va = "VA"
    case vi = "VI"
    case vt = "VT"
    case wa = "WA"
    case wi = "WI"
    case wv = "WV"
    case wy = "WY"
}

typealias Cities = [City]

Answer 1

您可以使用first(where:)-请注意，这会产生一个Optional

let result = try JSONDecoder().decode(Cities.self, from: jsonStr)

if let object = result.first(where: { $0.zipCode == 32071 }) {
    print(object.county) // prints "Suwannee"
}

如果要获得多个对象，可以使用 filter

let objects = result.filter { $0.zipCode == 32071 }