[Encoding] Introduce a builder pattern

JWT/JWT.swift

@@ -76,3 +76,79 @@ public func encode(payload:Payload, algorithm:Algorithm) -> String {
   let signature = algorithm.sign(signingInput)
   return "\(signingInput).\(signature)"
 }
+
+public class PayloadBuilder {
+  var payload = Payload()
+
+  public var issuer:String? {
+    get {
+      return payload["iss"] as? String
+    }
+    set {
+      payload["iss"] = newValue
+    }
+  }
+
+  public var audience:String? {
+    get {
+      return payload["aud"] as? String
+    }
+    set {
+      payload["aud"] = newValue
+    }
+  }
+
+  public var expiration:NSDate? {
+    get {
+      if let expiration = payload["exp"] as? NSTimeInterval {
+        return NSDate(timeIntervalSince1970: expiration)
+      }
+
+      return nil
+    }
+    set {
+      payload["exp"] = newValue?.timeIntervalSince1970
+    }
+  }
+
+  public var notBefore:NSDate? {
+    get {
+      if let notBefore = payload["nbf"] as? NSTimeInterval {
+        return NSDate(timeIntervalSince1970: notBefore)
+      }
+
+      return nil
+    }
+    set {
+      payload["nbf"] = newValue?.timeIntervalSince1970
+    }
+  }
+
+  public var issuedAt:NSDate? {
+    get {
+      if let issuedAt = payload["iat"] as? NSTimeInterval {
+        return NSDate(timeIntervalSince1970: issuedAt)
+      }
+
+      return nil
+    }
+    set {
+      payload["iat"] = newValue?.timeIntervalSince1970
+    }
+  }
+
+  public subscript(key: String) -> AnyObject? {
+    get {
+      return payload[key]
+    }
+    set {
+      payload[key] = newValue
+    }
+  }
+}
+
+public func encode(algorithm:Algorithm, closure:(PayloadBuilder -> ())) -> String {
+  let builder = PayloadBuilder()
+  closure(builder)
+  return encode(builder.payload, algorithm)
+}

JWTTests/JWTTests.swift

@@ -8,6 +8,69 @@ class JWTEncodeTests : XCTestCase {
     let fixture = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJuYW1lIjoiS3lsZSJ9.zxm7xcp1eZtZhp4t-nlw09ATQnnFKIiSN83uG8u6cAg"
     XCTAssertEqual(jwt, fixture)
   }
+
+  func testEncodingWithBuilder() {
+    let algorithm = Algorithm.HS256("secret")
+    let jwt = JWT.encode(algorithm) { builder in
+      builder.issuer = "fuller.li"
+    }
+
+    assertSuccess(JWT.decode(jwt, algorithm)) { payload in
+      XCTAssertEqual(payload as NSDictionary, ["iss": "fuller.li"])
+    }
+  }
+}
+
+class JWTPayloadBuilder : XCTestCase {
+  func testIssuer() {
+    JWT.encode(.None) { builder in
+       builder.issuer = "fuller.li"
+      XCTAssertEqual(builder.issuer!, "fuller.li")
+      XCTAssertEqual(builder["iss"] as String, "fuller.li")
+    }
+  }
+
+  func testAudience() {
+    JWT.encode(.None) { builder in
+      builder.audience = "cocoapods"
+      XCTAssertEqual(builder.audience!, "cocoapods")
+      XCTAssertEqual(builder["aud"] as String, "cocoapods")
+    }
+  }
+
+  func testExpiration() {
+    JWT.encode(.None) { builder in
+      let date = NSDate(timeIntervalSince1970: NSDate().timeIntervalSince1970)
+      builder.expiration = date
+      XCTAssertEqual(builder.expiration!, date)
+      XCTAssertEqual(builder["exp"] as NSTimeInterval, date.timeIntervalSince1970)
+    }
+  }
+
+  func testNotBefore() {
+    JWT.encode(.None) { builder in
+      let date = NSDate(timeIntervalSince1970: NSDate().timeIntervalSince1970)
+      builder.notBefore = date
+      XCTAssertEqual(builder.notBefore!, date)
+      XCTAssertEqual(builder["nbf"] as NSTimeInterval, date.timeIntervalSince1970)
+    }
+  }
+
+  func testIssuedAt() {
+    JWT.encode(.None) { builder in
+      let date = NSDate(timeIntervalSince1970: NSDate().timeIntervalSince1970)
+      builder.issuedAt = date
+      XCTAssertEqual(builder.issuedAt!, date)
+      XCTAssertEqual(builder["iat"] as NSTimeInterval, date.timeIntervalSince1970)
+    }
+  }
+
+  func testCustomAttributes() {
+    JWT.encode(.None) { builder in
+      builder["user"] = "kyle"
+      XCTAssertEqual(builder["user"] as String, "kyle")
+    }
+  }
 }
 
 class JWTDecodeTests : XCTestCase {

README.md

@@ -24,6 +24,16 @@ import JWT
 JWT.encode(["my": "payload"], .HS256("secret"))
 ```
 
+#### Building a JWT with the builder pattern
+
+```swift
+JWT.encode(.HS256("secret")) { builder in
+  builder.issuer = "fuller.li"
+  builder.issuedAt = NSDate()
+  builder["custom"] = "Hi"
+}
+```
+
 ### Decoding a JWT
 
 When decoding a JWT, you must supply one or more algorithms and keys.