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diff --git a/swift.html.markdown b/swift.html.markdown new file mode 100644 index 00000000..c7615a82 --- /dev/null +++ b/swift.html.markdown @@ -0,0 +1,224 @@ +--- +language: swift +contributors: + - ["Grant Timmerman", "http://github.com/grant"] +filename: learnswift.swift +--- + +Swift is a programming language for iOS and OS X development created by Apple. Designed to coexist with Objective-C and to be more resilient against erroneous code, Swift was introduced in 2014 at Apple's developer conference WWDC. It is built with the LLVM compiler included in Xcode 6 beta. + +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. + +# Overview +- [Basics](#basics) +- [Arrays and Dictionaries](#array) +- [Control Flow](#control) +- [Functions](#func) +- [Closures](#closures) +- [Classes](#classes) +- [Enums](#enums) +- [Other](#other) +- [Links](#links) + +## <a name="basics"></a>Basics + +```js +println("Hello, world") +var myVariable = 42 +let myConstant = 3.1415926 +let explicitDouble: Double = 70 +let label = "some text " + String(myVariable) // Casting +let piText = "Pi = \(myConstant)" // String interpolation +var optionalString: String? = "optional" // Can be nil +optionalString = nil +``` + +## <a name="array"></a>Arrays and Dictionaries + +```js +// Array +var shoppingList = ["catfish", "water", "lemons"] +shoppingList[1] = "bottle of water" +let emptyArray = String[]() + +// Dictionary +var occupations = [ + "Malcolm": "Captain", + "kaylee": "Mechanic" +] +occupations["Jayne"] = "Public Relations" +let emptyDictionary = Dictionary<String, Float>() +``` + +## <a name="control"></a>Control Flow + +```js +// for loop (array) +let myArray = [1, 1, 2, 3, 5] +for value in myArray { + if value == 1 { + println("One!") + } else { + println("Not one!") + } +} + +// for loop (dictionary) +for (key, value) in dict { + println("\(key): \(value)") +} + +// for loop (range) +for i in -1...1 { // [-1, 0, 1] + println(i) +} +// use .. to exclude the last number + +// while loop +var i = 1 +while i < 1000 { + i *= 2 +} + +// do-while loop +do { + println("hello") +} while 1 == 2 + +// Switch +let vegetable = "red pepper" +switch vegetable { +case "celery": + let vegetableComment = "Add some raisins and make ants on a log." +case "cucumber", "watercress": + let vegetableComment = "That would make a good tea sandwich." +case let x where x.hasSuffix("pepper"): + let vegetableComment = "Is it a spicy \(x)?" +default: // required (in order to cover all possible input) + let vegetableComment = "Everything tastes good in soup." +} +``` + +## <a name="functions"></a>Functions + +Functions are a first-class type, meaning they can be nested in functions and can be passed around + +```js +// Function +func greet(name: String, day: String) -> String { + return "Hello \(name), today is \(day)." +} +greet("Bob", "Tuesday") + +// Function that returns multiple items in a tuple +func getGasPrices() -> (Double, Double, Double) { + return (3.59, 3.69, 3.79) +} + +// Args +func setup(numbers: Int...) {} + +// Passing and returning functions +func makeIncrementer() -> (Int -> Int) { + func addOne(number: Int) -> Int { + return 1 + number + } + return addOne +} +var increment = makeIncrementer() +increment(7) +``` + +## <a name="closures"></a>Closures + +Functions are special case closures ({}) + +```js +// Closure example. +// `->` separates the arguments and return type +// `in` separates the closure header from the closure body +numbers.map({ + (number: Int) -> Int in + let result = 3 * number + return result + }) + +// When the type is known, like above, we can do this +var numbers = [1, 2, 6] +numbers = numbers.map({ number in 3 * number }) +print(numbers) // [3, 6, 18] +``` + +## <a name="classes"></a>Classes + +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` + +```js +// A simple class `Square` extends `Shape +class Rect: Shape { + var sideLength: Int = 1 + + // Custom getter and setter property + var perimeter: Int { + get { + return 4 * sideLength + } + set { + sideLength = newValue / 4 + } + } + + init(sideLength: Int) { + super.init() + self.sideLength = sideLength + } + + func shrink() { + if sideLength > 0 { + --sideLength + } + } + + override func getArea() -> Int { + return sideLength * sideLength + } +} +var mySquare = new Square(sideLength: 5) +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 an after getting or setting a property, you can use `willSet` and `didSet` +``` + +## <a name="enums"></a>Enums + +Enums can optionally be of a specific type or on their own. They can contain methods like classes. + +```js +enum Suit { + case Spades, Hearts, Diamonds, Clubs + func getIcon() -> String { + switch self { + case .Spades: return "♤" + case .Hearts: return "♡" + case .Diamonds: return "♢" + case .Clubs: return "♧" + } + } +} +``` + +## <a name="other"></a>Other + +- **`protocol`**: Similar to Java interfaces. +- **`extension`s**: Add extra functionality to an already created type +- **Generics**: Similar to Java. Use the `where` keyword to specify the requirements of the generics. + +## <a name="links"></a>Links + +- [Homepage](https://developer.apple.com/swift/) +- [Guide](https://developer.apple.com/library/prerelease/ios/referencelibrary/GettingStarted/LandingPage/index.html) +- [Book](https://itunes.apple.com/us/book/the-swift-programming-language/id881256329?mt=11) |