Pull request to extend the functionality

Demo/Demo/User.swift

@@ -16,6 +16,7 @@ struct User {
     var company: Company?
     var friends: [User] = []
     var website: NSURL?
+    var props: [String: String] = [:]
 }
 
 extension User: JSONCodable {
@@ -27,6 +28,7 @@ extension User: JSONCodable {
             company = try JSONDictionary.decode("company")
             friends = try JSONDictionary.decode("friends")
             website = try JSONDictionary.decode("website.url", transformer: JSONTransformers.StringToNSURL)
+            props = try JSONDictionary.decode("props")
         }
         catch {
             print(error)
@@ -42,6 +44,7 @@ extension User: JSONCodable {
         try result.encode(company, key: "company")
         try result.encode(friends, key: "friends")
         try result.encode(website, key: "website", transformer: JSONTransformers.StringToNSURL)
+        try result.encode(props, key: "props")
         return result
     }
 }

Demo/Demo/ViewController.swift

@@ -27,7 +27,8 @@ class ViewController: UIViewController {
                 ["id": 27, "full_name": "Bob Jefferson"],
                 ["id": 29, "full_name": "Jen Jackson"]
             ],
-            "website": ["url": "http://johnappleseed.com"]
+            "website": ["url": "http://johnappleseed.com"],
+            "props": ["prop a": "value a", "prop b": "value b"]
         ]
 
         print("Initial JSON:\n\(JSON)\n\n")

JSONCodable/JSONDecodable.swift

@@ -82,6 +82,28 @@ public extension Dictionary where Value: AnyObject {
         }
     }
 
+    // optional array of scalars
+    public func decode<Value: JSONCompatible>(key: Key) throws -> [String: Value]? {
+        if let y = get(key) ?? self[key] {
+            guard let x = y as? [String: Value] else {
+                throw JSONDecodableError.IncompatibleTypeError(key: key as! String, elementType: y.dynamicType, expectedType: [String: Value].self)
+            }
+            return x
+        }
+        return nil
+    }
+
+    // required dictionary of scalars
+    public func decode<Value: JSONCompatible>(key: Key) throws -> [String: Value] {
+        guard let y = get(key) ?? self[key] else {
+            throw JSONDecodableError.MissingTypeError(key: key as! String)
+        }
+        guard let x = y as? [String: Value] else {
+            throw JSONDecodableError.IncompatibleTypeError(key: key as! String, elementType: y.dynamicType, expectedType: [String: Value].self)
+        }
+        return x
+    }
+
     // TODO: validate array elements
     // optional array of decodables
     public func decode<Element: JSONDecodable>(key: Key) throws -> [Element]? {
@@ -130,6 +152,9 @@ public extension Dictionary where Value: AnyObject {
     // optional decodable
     public func decode<Type: JSONDecodable>(key: Key) throws -> Type? {
         if let y = get(key) ?? self[key] {
+            if y is NSNull {
+                return nil
+            }
             guard let x = y as? [String : AnyObject] else {
                 throw JSONDecodableError.DictionaryTypeExpectedError(key: key as! String, elementType: y.dynamicType)
             }

JSONCodable/JSONEncodable.swift

@@ -11,6 +11,7 @@
 public enum JSONEncodableError: ErrorType, CustomStringConvertible {
     case IncompatibleTypeError(elementType: Any.Type)
     case ArrayIncompatibleTypeError(elementType: Any.Type)
+    case DictionaryIncompatibleTypeError(elementType: Any.Type)
     case ChildIncompatibleTypeError(key: String, elementType: Any.Type)
     case TransformerFailedError(
         key: String
@@ -22,6 +23,8 @@ public enum JSONEncodableError: ErrorType, CustomStringConvertible {
             return "JSONEncodableError: Incompatible type \(elementType)"
         case let .ArrayIncompatibleTypeError(elementType: elementType):
             return "JSONEncodableError: Got an array of incompatible type \(elementType)"
+        case let .DictionaryIncompatibleTypeError(elementType: elementType):
+            return "JSONEncodableError: Got an dictionary of incompatible type \(elementType)"
         case let .ChildIncompatibleTypeError(key: key, elementType: elementType):
             return "JSONEncodableError: Got incompatible type \(elementType) for key \(key)"
         case let .TransformerFailedError(key: key):
@@ -77,6 +80,21 @@ public extension Array {//where Element: JSONEncodable {
 
 // Dictionary convenience methods
 
+public extension Dictionary {//where Key: String, Value: JSONEncodable {
+    public func toJSON() throws -> AnyObject {
+        var result: [String: AnyObject] = [:]
+        for (k, item) in self {
+            if let item = item as? JSONEncodable {
+                result[String(k)] = try item.toJSON()
+            }
+            else {
+                throw JSONEncodableError.DictionaryIncompatibleTypeError(elementType: item.dynamicType)
+            }
+        }
+        return result
+    }
+}
+
 public extension Dictionary where Value: AnyObject {
     public mutating func encode(value: Any, key: Key) throws {
         let actualValue: Any
@@ -107,6 +125,15 @@ public extension Dictionary where Value: AnyObject {
             self[key] = (result as! Value)
         }
 
+        // test for dictionary
+        else if let dict = actualValue as? JSONDictionary {
+            if dict.dictionaryIsJSONEncodable() {
+                let encodableDict = dict.dictionaryMadeJSONEncodable()
+                let result = try encodableDict.toJSON()
+                self[key] = (result as! Value)
+            }
+        }
+
         // incompatible type
         else {
             throw JSONEncodableError.ChildIncompatibleTypeError(key: key as! String, elementType: actualValue.dynamicType)

JSONCodable/JSONHelpers.swift

@@ -6,6 +6,27 @@
 //  Copyright © 2015 matthewcheok. All rights reserved.
 //
 
+// Dictionary handling
+
+protocol JSONDictionary {
+    func dictionaryIsJSONEncodable() -> Bool
+    func dictionaryMadeJSONEncodable() -> [String: JSONEncodable]
+}
+
+extension Dictionary : JSONDictionary {
+    func dictionaryIsJSONEncodable() -> Bool {
+        return Key.self is String.Type && Value.self is JSONEncodable.Type
+    }
+
+    func dictionaryMadeJSONEncodable() -> [String: JSONEncodable] {
+        var dict: [String: JSONEncodable] = [:]
+        for (k, v) in self {
+            dict[String(k)] = v as? JSONEncodable
+        }
+        return dict
+    }
+}
+
 // Array handling
 
 protocol JSONArray {

JSONCodable/JSONString.swift

@@ -10,12 +10,48 @@ import Foundation
 
 public extension JSONEncodable {
     public func toJSONString() throws -> String {
-        let json = try toJSON()
-        let data = try NSJSONSerialization.dataWithJSONObject(json, options: NSJSONWritingOptions(rawValue: 0))
-        guard let string = NSString(data: data, encoding: NSUTF8StringEncoding) else {
-            return ""
+        switch self {
+        case let str as String:
+            return escapeJSONString(str)
+        case is Bool, is Int, is Float, is Double:
+            return String(self)
+        default:
+            let json = try toJSON()
+            let data = try NSJSONSerialization.dataWithJSONObject(json, options: NSJSONWritingOptions(rawValue: 0))
+            guard let string = NSString(data: data, encoding: NSUTF8StringEncoding) else {
+                return ""
+            }
+            return string as String
+        }
+    }
+}
+
+private func escapeJSONString(str: String) -> String {
+    var chars = String.CharacterView("\"")
+    for c in str.characters {
+        switch c {
+        case "\\":
+            chars.append("\\")
+            chars.append("\\")
+        case "\"":
+            chars.append("\\")
+            chars.append("\"")
+        default:
+            chars.append(c)
+        }
+    }
+    chars.append("\"")
+    return String(chars)
+}
+
+public extension Optional where Wrapped: JSONEncodable {
+    public func toJSONString() throws -> String {
+        switch self {
+        case let .Some(jsonEncodable):
+            return try jsonEncodable.toJSONString()
+        case nil:
+            return "null"
         }
-        return string as String
     }
 }