proxpero · July 17, 2017 19:08 · Jul 17, 2017
diff --git a/Barcode2.swift b/Barcode2.swift
@@ -0,0 +1,85 @@
+// Accompanying blog post: http://127.0.0.1:4000/2017/07/11/encoding-and-decoding-custom-enums-with-associated-values-in-swift-4
+// Also: https://gist.github.com/proxpero/189a723fb96bb88fac5bf9e11d6cf9e2
+enum Barcode {
+    case upc(Int, Int, Int, Int)
+    case qrCode(String)
+}
+
+extension Barcode: Codable {
+
+    private enum CodingKeys: String, CodingKey {
+        case upc
+        case qrCode
+    }
+
+    enum CodingError: Error {
+        case decoding(String)
+    }
+
+    init(from decoder: Decoder) throws {
+        let values = try decoder.container(keyedBy: CodingKeys.self)
+        if let codes = try? values.decode(Array<Int>.self, forKey: .upc), codes.count == 4 {
+            self = .upc(codes[0], codes[1], codes[2], codes[3])
+            return
+        }
+
+        if let code = try? values.decode(String.self, forKey: .qrCode) {
+            self = .qrCode(code)
+            return
+        }
+
+        throw CodingError.decoding("Decoding Error: \(dump(values))")
+    }
+
+    func encode(to encoder: Encoder) throws {
+        var container = encoder.container(keyedBy: CodingKeys.self)
+        switch self {
+        case .upc(let numberSystem, let manufacturer, let product, let check):
+            try container.encode([numberSystem, manufacturer, product, check], forKey: .upc)
+        case .qrCode(let productCode):
+            try container.encode(productCode, forKey: .qrCode)
+        }
+    }
+}
+
+
+import Foundation
+
+let encoder = JSONEncoder()
+encoder.outputFormatting = .prettyPrinted
+let decoder = JSONDecoder()
+var productBarcode: Barcode
+var data: Data
+var json: String
+var expectation: String
+var result: Barcode
+
+productBarcode = .upc(8, 85909, 51226, 3)
+data = try encoder.encode(productBarcode)
+json = String.init(data: data, encoding: .utf8)!
+expectation = """
+{
+  "upc" : [
+    8,
+    85909,
+    51226,
+    3
+  ]
+}
+"""
+print(json)
+result = try decoder.decode(Barcode.self, from: data)
+//assert(result == productBarcode)
+
+
+productBarcode = .qrCode("ABCDEFGHIJKLMNOP")
+data = try encoder.encode(productBarcode)
+json = String.init(data: data, encoding: .utf8)!
+expectation = """
+{
+  "qrCode" : "ABCDEFGHIJKLMNOP"
+}
+"""
+result = try decoder.decode(Barcode.self, from: data)
+assert(json == expectation)
+////assert(result == productBarcode)