Merge remote-tracking branch 'adambard/master'

Conflicts:
	swift.html.markdown

1 files changed, 124 insertions, 40 deletions

diff --git a/swift.html.markdown b/swift.html.markdown
index 5e6b76e6..f2e9d04c 100644
--- a/swift.html.markdown
+++ b/swift.html.markdown
@@ -3,6 +3,10 @@ language: swift
 contributors:
   - ["Grant Timmerman", "http://github.com/grant"]
   - ["Christopher Bess", "http://github.com/cbess"]
+  - ["Joey Huang", "http://github.com/kamidox"]
+  - ["Anthony Nguyen", "http://github.com/anthonyn60"]
+  - ["Clayton Walker", "https://github.com/cwalk"]
+  - ["Fernando Valverde", "http://visualcosita.xyz"]
 filename: learnswift.swift
 ---
 
@@ -10,7 +14,7 @@ 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/DevelopiOSAppsSwift/), which has a complete tutorial on Swift.
 
 ```swift
 // import a module
@@ -22,10 +26,13 @@ import UIKit
 
 // Xcode supports landmarks to annotate your code and lists them in the jump bar
 // MARK: Section mark
+// MARK: - Section mark with a separator line
 // TODO: Do something soon
 // FIXME: Fix this code
 
-println("Hello, world")
+// In Swift 2, println and print were combined into one print method. Print automatically appends a new line.
+print("Hello, world") // println is now print
+print("Hello, world", appendNewLine: false) // printing without appending a newline
 
 // variables (var) value can change after being set
 // constants (let) value can NOT be changed after being set
@@ -45,16 +52,17 @@ let piText = "Pi = \(π), Pi 2 = \(π * 2)" // String interpolation
 // Build Specific values
 // uses -D build configuration
 #if false
-    println("Not printed")
+    print("Not printed")
     let buildValue = 3
 #else
     let buildValue = 7
 #endif
-println("Build value: \(buildValue)") // Build value: 7
+print("Build value: \(buildValue)") // Build value: 7
 
 /*
-    Optionals are a Swift language feature that allows you to store a `Some` or
-    `None` value.
+    Optionals are a Swift language feature that either contains a value,
+    or contains nil (no value) to indicate that a value is missing.
+    A question mark (?) after the type marks the value as optional.
 
     Because Swift requires every property to have a value, even nil must be
     explicitly stored as an Optional value.
@@ -68,13 +76,19 @@ var someOptionalString2: Optional<String> = "optional"
 if someOptionalString != nil {
     // I am not nil
     if someOptionalString!.hasPrefix("opt") {
-        println("has the prefix")
+        print("has the prefix")
     }
-    
+
     let empty = someOptionalString?.isEmpty
 }
 someOptionalString = nil
 
+/*
+    Trying to use ! to access a non-existent optional value triggers a runtime
+    error. Always make sure that an optional contains a non-nil value before
+    using ! to force-unwrap its value.
+*/
+
 // implicitly unwrapped optional
 var unwrappedString: String! = "Value is expected."
 // same as above, but ! is a postfix operator (more syntax candy)
@@ -89,13 +103,13 @@ if let someOptionalStringConstant = someOptionalString {
 
 // Swift has support for storing a value of any type.
 // AnyObject == id
-// Unlike Objective-C `id`, AnyObject works with any value (Class, Int, struct, etc)
+// Unlike Objective-C `id`, AnyObject works with any value (Class, Int, struct, etc.)
 var anyObjectVar: AnyObject = 7
 anyObjectVar = "Changed value to a string, not good practice, but possible."
 
 /*
     Comment here
-    
+
     /*
         Nested comments are also supported
     */
@@ -116,6 +130,7 @@ shoppingList[1] = "bottle of water"
 let emptyArray = [String]() // let == immutable
 let emptyArray2 = Array<String>() // same as above
 var emptyMutableArray = [String]() // var == mutable
+var explicitEmptyMutableStringArray: [String] = [] // same as above
 
 
 // Dictionary
@@ -127,6 +142,7 @@ occupations["Jayne"] = "Public Relations"
 let emptyDictionary = [String: Float]() // let == immutable
 let emptyDictionary2 = Dictionary<String, Float>() // same as above
 var emptyMutableDictionary = [String: Float]() // var == mutable
+var explicitEmptyMutableDictionary: [String: Float] = [:] // same as above
 
 
 //
@@ -137,21 +153,21 @@ var emptyMutableDictionary = [String: Float]() // var == mutable
 let myArray = [1, 1, 2, 3, 5]
 for value in myArray {
     if value == 1 {
-        println("One!")
+        print("One!")
     } else {
-        println("Not one!")
+        print("Not one!")
     }
 }
 
 // for loop (dictionary)
 var dict = ["one": 1, "two": 2]
 for (key, value) in dict {
-    println("\(key): \(value)")
+    print("\(key): \(value)")
 }
 
 // for loop (range)
 for i in -1...shoppingList.count {
-    println(i)
+    print(i)
 }
 shoppingList[1...2] = ["steak", "peacons"]
 // use ..< to exclude the last number
@@ -164,7 +180,7 @@ while i < 1000 {
 
 // do-while loop
 do {
-    println("hello")
+    print("hello")
 } while 1 == 2
 
 // Switch
@@ -221,8 +237,8 @@ let pricesTuple = getGasPrices()
 let price = pricesTuple.2 // 3.79
 // Ignore Tuple (or other) values by using _ (underscore)
 let (_, price1, _) = pricesTuple // price1 == 3.69
-println(price1 == pricesTuple.1) // true
-println("Gas price: \(price)")
+print(price1 == pricesTuple.1) // true
+print("Gas price: \(price)")
 
 // Named tuple params
 func getGasPrices2() -> (lowestPrice: Double, highestPrice: Double, midPrice: Double) {
@@ -260,7 +276,7 @@ func swapTwoInts(inout a: Int, inout b: Int) {
 var someIntA = 7
 var someIntB = 3
 swapTwoInts(&someIntA, &someIntB)
-println(someIntB) // 7
+print(someIntB) // 7
 
 
 //
@@ -301,10 +317,10 @@ print(numbers) // [3, 6, 18]
 // MARK: Structures
 //
 
-// Structures and classes have very similar capabilites
+// Structures and classes have very similar capabilities
 struct NamesTable {
     let names = [String]()
-    
+
     // Custom subscript
     subscript(index: Int) -> String {
         return names[index]
@@ -314,7 +330,7 @@ struct NamesTable {
 // Structures have an auto-generated (implicit) designated initializer
 let namesTable = NamesTable(names: ["Me", "Them"])
 let name = namesTable[1]
-println("Name is \(name)") // Name is Them
+print("Name is \(name)") // Name is Them
 
 //
 // MARK: Classes
@@ -335,7 +351,7 @@ public class Shape {
 
 internal class Rect: Shape {
     var sideLength: Int = 1
-    
+
     // Custom getter and setter property
     private var perimeter: Int {
         get {
@@ -346,16 +362,16 @@ internal class Rect: Shape {
             sideLength = newValue / 4
         }
     }
-    
-    // Computed properties must be declared as `var`, you know, cause they can change
+
+    // Computed properties must be declared as `var`, you know, cause' they can change
     var smallestSideLength: Int {
         return self.sideLength - 1
     }
-    
+
     // Lazily load a property
     // subShape remains nil (uninitialized) until getter called
     lazy var subShape = Rect(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`
@@ -365,19 +381,19 @@ internal class Rect: Shape {
             print(someIdentifier)
         }
     }
-    
+
     init(sideLength: Int) {
         self.sideLength = sideLength
         // always super.init last when init custom properties
         super.init()
     }
-    
+
     func shrink() {
         if sideLength > 0 {
             --sideLength
         }
     }
-    
+
     override func getArea() -> Int {
         return sideLength * sideLength
     }
@@ -400,7 +416,36 @@ let aShape = mySquare as Shape
 
 // compare instances, not the same as == which compares objects (equal to)
 if mySquare === mySquare {
-    println("Yep, it's mySquare")
+    print("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)
+print(myCircle?.getArea())    // Optional(3)
+print(myCircle!.getArea())    // 3
+var myEmptyCircle = Circle(radius: -1)
+print(myEmptyCircle?.getArea())    // "nil"
+if let circle = myEmptyCircle {
+    // will not execute since myEmptyCircle is nil
+    print("circle is not nil")
 }
 
 
@@ -432,7 +477,29 @@ enum BookName: String {
     case John = "John"
     case Luke = "Luke"
 }
-println("Name: \(BookName.John.rawValue)")
+print("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)
+print(desk.description())     // "Desk with 80 cm"
+var chair = Furniture.Chair("Foo", 40)
+print(chair.description())    // "Chair of Foo with 40 cm"
 
 
 //
@@ -457,10 +524,13 @@ protocol ShapeGenerator {
 
 class MyShape: Rect {
     var delegate: TransformShape?
-    
+
     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?()
@@ -482,21 +552,21 @@ extension Square: Printable {
     }
 }
 
-println("Square: \(mySquare)")
+print("Square: \(mySquare)")
 
 // You can also extend built-in types
 extension Int {
     var customProperty: String {
         return "This is \(self)"
     }
-    
+
     func multiplyBy(num: Int) -> Int {
         return num * self
     }
 }
 
-println(7.customProperty) // "This is 7"
-println(14.multiplyBy(2)) // 42
+print(7.customProperty) // "This is 7"
+print(14.multiplyBy(3)) // 42
 
 // Generics: Similar to Java and C#. Use the `where` keyword to specify the
 //   requirements of the generics.
@@ -510,7 +580,7 @@ func findIndex<T: Equatable>(array: [T], valueToFind: T) -> Int? {
     return nil
 }
 let foundAtIndex = findIndex([1, 2, 3, 4], 3)
-println(foundAtIndex == 2) // true
+print(foundAtIndex == 2) // true
 
 // Operators:
 // Custom operators can start with the characters:
@@ -526,9 +596,23 @@ prefix func !!! (inout shape: Square) -> Square {
 }
 
 // current value
-println(mySquare.sideLength) // 4
+print(mySquare.sideLength) // 4
 
 // change side length using custom !!! operator, increases size by 3
 !!!mySquare
-println(mySquare.sideLength) // 12
+print(mySquare.sideLength) // 12
+
+// Operators can also be generics
+infix operator <-> {}
+func <-><T: Equatable> (inout a: T, inout b: T) {
+    let c = a
+    a = b
+    b = c
+}
+
+var foo: Float = 10
+var bar: Float = 20
+
+foo <-> bar
+print("foo is \(foo), bar is \(bar)") // "foo is 20.0, bar is 10.0"
 ```