json-key-decoding-strategy.swift

json-key-decoding-strategy.swift

struct AnyKey: CodingKey {

      static let empty = AnyKey(string: "")

      var stringValue: String
     var intValue: Int?

      init?(stringValue: String) {
         self.stringValue = stringValue
         self.intValue = nil
     }

      init?(intValue: Int) {
         self.stringValue = String(intValue)
         self.intValue = intValue
     }

      init(string: String) {
         self.stringValue = string
         self.intValue = nil
     }

  }

  public extension JSONDecoder.KeyDecodingStrategy {

      static let convertFromKebabCase = JSONDecoder.KeyDecodingStrategy.custom({ keys in
         // Should never receive an empty `keys` array in theory.
         guard let lastKey = keys.last else {
             return AnyKey.empty
         }
         // Represents an array index.
         if lastKey.intValue != nil {
             return lastKey
         }
         let components = lastKey.stringValue.split(separator: "-")
         guard let firstComponent = components.first?.lowercased() else {
             return lastKey
         }
         let trailingComponents = components.dropFirst().map {
             $0.capitalized
         }
         let lowerCamelCaseKey = ([firstComponent] + trailingComponents).joined()
         return AnyKey(string: lowerCamelCaseKey)
     })

  }