delegate object for model decoding functions

MVMCore/MVMCore/Models/Extensions/Decoder.swift

@@ -61,4 +61,26 @@ extension Decodable {
     }
 }
 
+public enum DecoderKeyError: Error {
+    case createKey
+}
 
+public extension JSONDecoder {
+    /// Adds a delegate object to the decoder for use in the model initializers.
+    func add<T: DelegateObject>(delegateObject: T) throws {
+        guard let key = CodingUserInfoKey(rawValue: "delegateObject") else {
+            throw DecoderKeyError.createKey
+        }
+        userInfo.updateValue(delegateObject, forKey: key)
+    }
+}
+
+public extension Decoder {
+    /// Gets a delegate object from the decoder for use in the model initializers. Had to be added before decode.
+    func get<T: DelegateObject>() throws -> T? {
+        guard let key = CodingUserInfoKey(rawValue: "delegateObject") else {
+            throw DecoderKeyError.createKey
+        }
+        return userInfo[key] as? T
+    }
+}