A swift introduction to Swift

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A quick introduction to Swift, the new language Apple introduced in WWDC14 to create apps for iOS and OSX

A swift introduction to Swift

  1. A swift introduction to Giordano Scalzo Closure Busker
  2. iOS Dev geek giordano.scalzo@gmail.com
  3. with different reactions
  4. but also
  5. From
  6. To
  7. What does Swift look like?
  8. SHOW ME THE CODE!!!!!
  9. let individualScores = [75, 43, 103, 87, 12] var teamScore = 0 for score in individualScores { if score > 50 { teamScore += 3 } else { teamScore += 1 } } teamScore
  10. ;
  11. ;
  12. var optionalName: String? = "John Appleseed" var greeting = "Hello!" ! if optionalName { greeting = "Hello, (optionalName!)" } Optional
  13. var optionalName: String? = "John Appleseed" var greeting = "Hello!" ! if let name = optionalName { greeting = "Hello, (name)" } Optional
  14. if let upper = john.residence?.address?.buildingIdentifier()?.uppercaseString { println("John's uppercase building identifier is (upper).") } else { println("I can't find John's address") } Optional Chaining
  15. Playground
  16. Switch on steroids
  17. let vegetable = "red pepper" switch vegetable { case "celery": let vegetableComment = "Add raisins." case "cucumber", "watercress": let vegetableComment = "sandwich." case let x where x.hasSuffix("pepper"): let vegetableComment = "Is it a spicy (x)?" default: let vegetableComment = "Soup." }
  18. let somePoint = (1, 1) switch somePoint { case (0, 0): println("(0, 0) is at the origin") case (_, 0): println("((somePoint.0), 0) is on the x-axis") case (0, _): println("(0, (somePoint.1)) is on the y-axis") case (-2...2, -2...2): println("((somePoint.0), (somePoint.1)) is inside the box") default: println("((somePoint.0), (somePoint.1)) is outside of the box") }
  19. Functions and closures
  20. func greet(name: String, #day: String) -> String { return "Hello (name), today is (day)." } greet("Bob", day: "Wednesday") Named Parameters
  21. func greet(name: String, day: String) -> String { return "Hello (name), today is (day)." } greet("Bob", "Wednesday") Named Parameters Optional
  22. Multiple result using tuples func getGasPrices()->(Double, Double, Double) { return (3.59, 3.69, 3.79) } let (min, avg, max) = getGasPrices() println("min is (min), max is (max)")
  23. Multiple result using tuples func getGasPrices()->(Double, Double, Double) { return (3.59, 3.69, 3.79) } let gasPrices = getGasPrices() println("min is (gasPrices.0), max is (gasPrices.2)")
  24. Functions are first class type
  25. func makeIncrementer() -> (Int -> Int) { func addOne(number: Int) -> Int { return 1 + number } return addOne } var increment = makeIncrementer() increment(7) A function can be a return value
  26. or a function parameter func hasAnyMatches(list: Int[], condition: Int -> Bool) -> Bool { for item in list { if condition(item) { return true } } return false } func lessThanTen(number: Int) -> Bool { return number < 10 } var numbers = [20, 19, 7, 12] hasAnyMatches(numbers, lessThanTen)
  27. anonymous function func hasAnyMatches(list: Int[], condition: Int -> Bool) -> Bool { for item in list { if condition(item) { return true } } return false } func lessThanTen(number: Int) -> Bool { return number < 10 } var numbers = [20, 19, 7, 12] hasAnyMatches(numbers, { num in num < 10})
  28. func hasAnyMatches(list: Int[], condition: Int -> Bool) -> Bool { for item in list { if condition(item) { return true } } return false } func lessThanTen(number: Int) -> Bool { return number < 10 } var numbers = [20, 19, 7, 12] hasAnyMatches(numbers) { num in num < 10} anonymous function
  29. func hasAnyMatches(list: Int[], condition: Int -> Bool) -> Bool { for item in list { if condition(item) { return true } } return false } func lessThanTen(number: Int) -> Bool { return number < 10 } var numbers = [20, 19, 7, 12] hasAnyMatches(numbers) { $0 < 10} anonymous function
  30. Where are the classes?
  31. class NamedShape { var numberOfSides: Int = 0 var name: String init(name: String) { self.name = name } func simpleDescription() -> String { return "A shape with (numberOfSides) sides." } }
  32. class Square: NamedShape { var sideLength: Double init(sideLength: Double, name: String) { self.sideLength = sideLength super.init(name: name) numberOfSides = 4 } func area() -> Double { return sideLength * sideLength } override func simpleDescription() -> String { return "A square with sides of length (sideLength)." } } ! let test = Square(sideLength: 5.2, name: "my test square") test.area() test.simpleDescription()
  33. class Square: NamedShape { var sideLength: Double init(sideLength len: Double, name: String) { self.sideLength = len super.init(name: name) numberOfSides = 4 } func area() -> Double { return sideLength * sideLength } override func simpleDescription() -> String { return "A square with sides of length (sideLength)." } } ! let test = Square(sideLength: 5.2, name: "my test square") test.area() test.simpleDescription()
  34. class Square: NamedShape { var sideLength: Double init(_ sideLength: Double, _ name: String) { self.sideLength = sideLength super.init(name: name) numberOfSides = 4 } func area() -> Double { return sideLength * sideLength } override func simpleDescription() -> String { return "A square with sides of length (sideLength)." } } ! let test = Square(5.2, "my test square") test.area() test.simpleDescription()
  35. class EquilateralTriangle: NamedShape { var sideLength: Double = 0.0 ... var perimeter: Double { get { return 3.0 * sideLength } set { sideLength = newValue / 3.0 } } ... } calculated properties
  36. class TriangleAndSquare { var triangle: EquilateralTriangle { willSet { square.sideLength = newValue.sideLength } } var square: Square { willSet { triangle.sideLength = newValue.sideLength } } } observable properties
  37. struct Card { var rank: Rank var suit: Suit func simpleDescription() -> String { return "The (rank.simpleDescription()) of (suit.simpleDescription())" } } let threeOfSpades = Card(rank: Card.Three, suit: Card.Spades) let threeOfSpadesDescription = threeOfSpades.simpleDescription() Structs
  38. struct Card { var rank: Rank var suit: Suit func simpleDescription() -> String { return "The (rank.simpleDescription()) of (suit.simpleDescription())" } } let threeOfSpades = Card(rank: .Three, suit: .Spades) let threeOfSpadesDescription = threeOfSpades.simpleDescription() Structs
  39. like classes, but passed by value...in a smarter way
  40. classes are always passed by reference structs are passed by reference, but automatically copied when mutated
  41. Struct are used as ValueTypes, data components manipulated by classes
  42. https://www.destroyallsoftware.com/talks/boundaries
  43. enum Rank: Int { case Ace = 1 case Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten case Jack, Queen, King func simpleDescription() -> String { switch self { case .Ace: return "ace" case .Jack: return "jack" case .Queen: return "queen" case .King: return "king" default: return String(self.toRaw()) } } } Enumerations on steroids
  44. enum ServerResponse { case Result(String, String) case Error(String) } Enumerations with a value associated
  45. Enumerations with a value associated let success = ServerResponse.Result("6:00 am", "8:09 pm") let failure = ServerResponse.Error("Out of cheese.")
  46. Pattern matching to extract associated values switch result { case let .Result(sunrise, sunset): let serverResponse = "Sunrise is at (sunrise) and sunset is at (sunset)." case let .Error(error): let serverResponse = "Failure... (error)" }
  47. protocol ExampleProtocol { var simpleDescription: String { get } mutating func adjust() } Protocols... like Interface in Java or... protocols in Objective-C
  48. extension Int: ExampleProtocol { var simpleDescription: String { return "The number (self)" } mutating func adjust() { self += 42 } } 7.simpleDescription extensions... like categories in Objective-C
  49. Generics
  50. func repeatString(item: String, times: Int) -> String[] { var result = String[]() for i in 0..times { result += item } return result } repeatString("knock", 4)
  51. ! func repeatInt(item: Int, times: Int) -> Int[] { var result = Int[]() for i in 0..times { result += item } return result } repeatInt(42, 4)
  52. func repeat<T>(item: T, times: Int) -> T[] { var result = T[]() for i in 0..times { result += item } return result } repeat("knock", 4) repeat(42, 3)
  53. Operator overload @infix func +(t1: Int, t2: Int) -> Int{ return 3 } ! @prefix func +(t1: Int) -> Int{ return 5 } ! var a = 20 var b = 111 ! a + b // 3 a - +b // 15
  54. But the most important feature, the only one that you need to learn is...
  55. Emoji!!!
  56. For me (imvho) the most useful new features are enumerations and pattern matching
  57. Unit Test support
  58. XCTest class RpnCalculatorKataTests: XCTestCase { override func setUp() { super.setUp() } override func tearDown() { super.tearDown() } func testExample() { XCTAssert(true, "Pass") } func testPerformanceExample() { self.measureBlock() { } } }
  59. Quick class PersonSpec: QuickSpec { override class func exampleGroups() { describe("Person") { var person: Person? beforeEach { person = Person() } describe("greeting") { context("when the person is unhappy") { beforeEach { person!.isHappy = false } it("is lukewarm") { expect(person!.greeting).to.equal("Oh, hi.") expect(person!.greeting).notTo.equal("Hello!") } } } } } }
  60. And now...
  61. Let's code
  62. a Rpn Calculator
  63. enum Key : String { case One = "1" //... case Enter = "enter" case Plus = "+" case Minus = "-" } ! protocol RpnCalculator { var display : String[] { get } func press(key: Key) } https://github.com/gscalzo/RpnCalculatorKata
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