迅捷的4个Firebase GeoPoint解码 [英] swift 4 firebase GeoPoint decode

问题描述

我想知道是否可以使用标准swift 4从Firebase的JSON响应中编码和解码GeoPoint?

I was wondering if it is possible to encode and decode a GeoPoint from the firebase's JSON response using standard swift 4?

到目前为止，GeoPoint似乎不可编码吗?

It looks like as of now that the GeoPoint is not Codable?

我收到以下错误

No 'decode' candidates produce the expected contextual result type 'GeoPoint'

在我的可编码课程中

final class Data: Codable
{
  var location:GeoPoint = GeoPoint(latitude:0,longitude:0)

  private enum CodingKeys: String, CodingKey
  {
    case geoloc
  }

  init(from decoder: Decoder) throws
  {
    let values = try decoder.container(keyedBy: CodingKeys.self)

    do
    {
      located = try values.decode(Location.self, forKey: .geoloc) //error here
    }
    catch
    {
      print("data has location in server response\n")
    }

  }

  func encode(to encoder: Encoder) throws
  {
    var container = encoder.container(keyedBy: CodingKeys.self)
    try container.encode(location, forKey: .geoloc)

  }
}

推荐答案

我能够扩展GeoPoint类并使其可编码.这就是我解决的方法.

I was able to extend the GeoPoint class and make it Codable. That is how I solved it.

import UIKit

final class MyGeoPoint: GeoPoint, Codable
{
  override init(latitude: Double, longitude: Double)
  {
    super.init(latitude: latitude, longitude: longitude)
  }

  private enum CodingKeys: String, CodingKey
  {
    case latitude  = "_latitude"
    case longitude = "_longitude"
  }

  init(from decoder: Decoder) throws
  {
    let container = try decoder.container(keyedBy: CodingKeys.self)
    var lat:Double   = 0
    var lon:Double  = 0

    do
    {
      lat = try container.decode(Double.self, forKey: .latitude)
    }
    catch
    {
      print("no latitude for MyGeoPoint")
    }

    do
    {
      lon = try container.decode(Double.self, forKey: .longitude)
    }
    catch
    {
      print("no longitude for MyGeoPoint")
    }


    super.init(latitude: lat, longitude: lon)
  }

  func encode(to encoder: Encoder) throws
  {
    var container = encoder.container(keyedBy: CodingKeys.self)
    try container.encode(latitude,  forKey: .latitude)
    try container.encode(longitude, forKey: .longitude)
  }

}

现在，我可以使用扩展的MyGeoPoint类(而不是直接使用Google的GeoPoint)来使用原始的Data类来使用Google的JSON响应

Now I can use my original Data class to consume the JSON response from Google, using my extended MyGeoPoint class (instead of Google's GeoPoint directly)

final class Data: Codable
{
  var location:MyGeoPoint = MyGeoPoint(latitude:0,longitude:0)
  private enum CodingKeys: String, CodingKey
  {
    case geoloc
  }
  init(from decoder: Decoder) throws
  {
    let values = try decoder.container(keyedBy: CodingKeys.self)

    do
    {
      //no error here anymore
      location = try values.decode(MyGeoPoint.self, forKey: .geoloc) 
    }
    catch
    {
      print("data has location in server response\n")
    }

  }

  func encode(to encoder: Encoder) throws
  {
    var container = encoder.container(keyedBy: CodingKeys.self)
    try container.encode(location, forKey: .geoloc)

  }
}

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