1 files changed, 58 insertions, 3 deletions

diff --git a/swift.html.markdown b/swift.html.markdown
index 0d1d2df4..ffc57e69 100644
--- a/swift.html.markdown
+++ b/swift.html.markdown
@@ -3,6 +3,7 @@ language: swift
 contributors:
   - ["Grant Timmerman", "http://github.com/grant"]
   - ["Christopher Bess", "http://github.com/cbess"]
+  - ["Joey Huang", "http://github.com/kamidox"]  
 filename: learnswift.swift
 ---
 
@@ -10,7 +11,7 @@ Swift is a programming language for iOS and OS X development created by Apple. D
 
 The official [Swift Programming Language](https://itunes.apple.com/us/book/swift-programming-language/id881256329) book from Apple is now available via iBooks.
 
-See also Apple's [getting started guide](https://developer.apple.com/library/prerelease/ios/referencelibrary/GettingStarted/LandingPage/index.html), which has a complete tutorial on Swift.
+See also Apple's [getting started guide](https://developer.apple.com/library/prerelease/ios/referencelibrary/GettingStarted/RoadMapiOS/index.html), which has a complete tutorial on Swift.
 
 ```swift
 // import a module
@@ -388,6 +389,35 @@ if mySquare === mySquare {
     println("Yep, it's mySquare")
 }
 
+// Optional init
+class Circle: Shape {
+    var radius: Int
+    override func getArea() -> Int {
+        return 3 * radius * radius
+    }
+    
+    // Place a question mark postfix after `init` is an optional init
+    // which can return nil
+    init?(radius: Int) {
+        self.radius = radius
+        super.init()
+        
+        if radius <= 0 {
+            return nil
+        }
+    }
+}
+
+var myCircle = Circle(radius: 1)
+println(myCircle?.getArea())    // Optional(3)
+println(myCircle!.getArea())    // 3
+var myEmptyCircle = Circle(radius: -1)
+println(myEmptyCircle?.getArea())    // "nil"
+if let circle = myEmptyCircle {
+    // will not execute since myEmptyCircle is nil
+    println("circle is not nil")
+}
+
 
 //
 // MARK: Enums
@@ -419,6 +449,28 @@ enum BookName: String {
 }
 println("Name: \(BookName.John.rawValue)")
 
+// Enum with associated Values
+enum Furniture {
+    // Associate with Int
+    case Desk(height: Int)
+    // Associate with String and Int
+    case Chair(String, Int)
+    
+    func description() -> String {
+        switch self {
+        case .Desk(let height):
+            return "Desk with \(height) cm"
+        case .Chair(let brand, let height):
+            return "Chair of \(brand) with \(height) cm"
+        }
+    }
+}
+
+var desk: Furniture = .Desk(height: 80)
+println(desk.description())     // "Desk with 80 cm"
+var chair = Furniture.Chair("Foo", 40)
+println(chair.description())    // "Chair of Foo with 40 cm"
+
 
 //
 // MARK: Protocols
@@ -445,7 +497,10 @@ class MyShape: Rect {
     
     func grow() {
         sideLength += 2
-        
+
+        // Place a question mark after an optional property, method, or
+        // subscript to gracefully ignore a nil value and return nil
+        // instead of throwing a runtime error ("optional chaining").
         if let allow = self.delegate?.canReshape?() {
             // test for delegate then for method
             self.delegate?.reshaped?()
@@ -481,7 +536,7 @@ extension Int {
 }
 
 println(7.customProperty) // "This is 7"
-println(14.multiplyBy(2)) // 42
+println(14.multiplyBy(3)) // 42
 
 // Generics: Similar to Java and C#. Use the `where` keyword to specify the
 //   requirements of the generics.