- add more examples; update examples

- now runs in the Xcode 6 b6 playground
- add MARK sections

swift.html.markdown

@@ -2,6 +2,7 @@
 language: swift
 contributors:
   - ["Grant Timmerman", "http://github.com/grant"]
+  - ["Christopher Bess", "http://github.com/cbess"]
 filename: learnswift.swift
 ---
 
@@ -11,21 +12,34 @@ See also Apple's [getting started guide](https://developer.apple.com/library/pre
 
 ```js
 //
-// Basics
+// MARK: Basics
 //
 
 println("Hello, world")
+
 var myVariable = 42
+//let fƒ∆ = "value" // unicode in variable names
 let myConstant = 3.1415926
+let convenience = "keyword" // contextual variable name
+let weak = "keyword"; let override = "another keyword" // statements can be separated by a semi-colon
+let `class` = "keyword" // backticks allow keywords to be used as variable names
 let explicitDouble: Double = 70
+let intValue = 0007 // 7
+let largeIntValue = 77_000 // 77000
 let label = "some text " + String(myVariable)     // Casting
 let piText = "Pi = \(myConstant)"                 // String interpolation
 var optionalString: String? = "optional"          // Can be nil
 optionalString = nil
 
+/*
+Comment here
+    /*
+        Nested comment here
+    */
+*/
 
 //
-// Arrays and Dictionaries
+// MARK: Collections
 //
 
 // Array
@@ -43,7 +57,7 @@ let emptyDictionary = Dictionary<String, Float>()
 
 
 //
-// Control Flow
+// MARK: Control Flow
 //
 
 // for loop (array)
@@ -57,6 +71,7 @@ for value in myArray {
 }
 
 // for loop (dictionary)
+var dict = ["one": 1, "two": 2]
 for (key, value) in dict {
     println("\(key): \(value)")
 }
@@ -93,7 +108,7 @@ default: // required (in order to cover all possible input)
 
 
 //
-// Functions
+// MARK: Functions
 //
 
 // Functions are a first-class type, meaning they can be nested
@@ -110,7 +125,7 @@ func getGasPrices() -> (Double, Double, Double) {
     return (3.59, 3.69, 3.79)
 }
 
-// Args
+// Variadic Args
 func setup(numbers: Int...) {}
 
 // Passing and returning functions
@@ -125,7 +140,7 @@ increment(7)
 
 
 //
-// Closures
+// MARK: Closures
 //
 var numbers = [1, 2, 6]
 
@@ -147,11 +162,27 @@ numbers = numbers.map({ number in 3 * number })
 
 print(numbers) // [3, 6, 18]
 
+// Trailing closure
+numbers = sorted(numbers) { $0 > $1 }
+
+print(numbers) // [18, 6, 3]
+
+// Super shorthand, since the < operator infers the types
+
+numbers = sorted(numbers, < )
+
+print(numbers) // [3, 6, 18]
 
 //
-// Classes
+// MARK: Classes
 //
 
+class Shape {
+    func getArea() -> Int {
+        return 0;
+    }
+}
+
 // All methods and properties of a class are public.
 // If you just need to store data in a
 // structured object, you should use a `struct`
@@ -170,6 +201,15 @@ class Rect: Shape {
         }
     }
     
+    // If you don't need a custom getter and setter,
+    // but still want to run code before and after getting or setting
+    // a property, you can use `willSet` and `didSet`
+    var identifier: String = "defaultID" {
+        willSet(someIdentifier) {
+            print(someIdentifier)
+        }
+    }
+    
     init(sideLength: Int) {
         super.init()
         self.sideLength = sideLength
@@ -185,18 +225,21 @@ class Rect: Shape {
         return sideLength * sideLength
     }
 }
-var mySquare = new Square(sideLength: 5)
+
+class Square: Rect {
+    convenience init() {
+        self.init(sideLength: 5)
+    }
+}
+
+var mySquare = Square()
 print(mySquare.getArea()) // 25
 mySquare.shrink()
 print(mySquare.sideLength) // 4
 
-// If you don't need a custom getter and setter,
-// but still want to run code before and after getting or setting
-// a property, you can use `willSet` and `didSet`
-
 
 //
-// Enums
+// MARK: Enums
 //
 
 // Enums can optionally be of a specific type or on their own.
@@ -216,12 +259,33 @@ enum Suit {
 
 
 //
-// Other
+// MARK: Other
 //
 
 // `protocol`: Similar to Java interfaces.
-// `extension`s: Add extra functionality to an already created type
+protocol ShapeGenerator {
+    func buildShape() -> Shape
+}
+
+// `extension`s: Add extra functionality to an already existing type
+extension Square: Printable {
+    var description: String {
+        return "Area: \(self.getArea()) - ID: \(self.identifier)"
+    }
+}
+
+println("Square: \(mySquare)")
+
 // Generics: Similar to Java. Use the `where` keyword to specify the
 //   requirements of the generics.
 
+func findIndex<T: Equatable>(array: [T], valueToFind: T) -> Int? {
+    for (index, value) in enumerate(array) {
+        if value == valueToFind {
+            return index
+        }
+    }
+    return nil
+}
+
 ```