Deep Dive Into Swift - Presented at Coffee@DBG In the previous month, Coffe@DBG Covered the basics of Swift, Apple's new programming language. This session introduces some of handpicked interesting features of Swift.

1. Deep Dive Into
Swift

2. @sarat
Software Architect

3. A bit of history

4. Chris Lattner
• Author of the original
LLVM tool chain project
• Started working on Swift
in 2010
• A research intern at
Microsoft Research
• Leads Development Tool
Effort at Apple

5. Why Swift?

6. Modern Compilers and
Optimization
Techniques

7. Influenced by Python,
Ruby, Objective-C, C#
etc.

8. Productivity
+
Native Performance

9. easy to learn

10. Playground & REPL

11. Playground

12. REPL (Read-Eval-Print-Loop)
- Write it in lldb when program runs
- Use xcrun swift to run externally

13. Transparent
interaction with
Objective-C & C

14. can deploy to previous
version of iOS and OS X

15. wide adoption in
short time

16. – The RedMonk Programming Language Rankings: January 2015
“Swift has gone from our 68th ranked
language during Q3 to number 22 this
quarter, a jump of 46 spots.”

17. Why Swift Performs
better?

18. Smaller Runtime

19. generates native
code

20. Swift Compiler
Architecture

23. Enumerations

24. similar to other
languages

25. enum CompassPoint {
case North
case South
case East
case West
}

26. enum CompassPoint {
case North
case South
case East
case West
}
var directionToHead = CompassPoint.East;
directionToHead = .East;

27. enum CompassPoint {
case North
case South
case East
case West
}
var directionToHead = CompassPoint.East;
directionToHead = .East;
switch(directionToHead) {
case .East:
println( "Heading east")
case .West:
println( "Heading West")
case .North:
println( "Heading North")
case .South:
println( "Heading South")
default:
println("Nowhere to go")
}

28. associated values

29. Enumerations can store associated
values of any given type.
The type can be different for each
member in the enumeration

30. // Associated Values Examples
enum Barcode {
case UPCA(Int, Int, Int, Int)
case QRCode(String)
}

31. // Associated Values Examples
enum Barcode {
case UPCA(Int, Int, Int, Int)
case QRCode(String)
}
var productBarcode = Barcode.UPCA(8, 85909, 51226, 3)
productBarcode = .QRCode("ABCDEFGHIJ")

32. // Associated Values Examples
enum Barcode {
case UPCA(Int, Int, Int, Int)
case QRCode(String)
}
var productBarcode = Barcode.UPCA(8, 85909, 51226, 3)
productBarcode = .QRCode("ABCDEFGHIJ")
let numberSystem = 8, manufacturer = 85909,
product = 51226, check = 3
switch productBarcode {
case let .UPCA(numberSystem, manufacturer, product, check)
println("UPCA Detected")
case let .QRCode("ABCDEFGHIJ")
println("QRCode detected")
}

33. switch-case pattern
matching

34. // Pattern Matching with Switch-Case
let x = 9
switch(x) {
case 1...5: // Closed range operator
println( "Range - 1,2,3,4,5")
case 6..<10: // Half closed range operator
println( "Range - 6,7,8,9")
default:
println("Default")
}

35. Properties

36. associates values with
classes, structure or
enumerations

37. Stored Properties
store constant and
variable values

38. Lazy Stored Properties
• Initializes on first time access
• Declared with lazy keyword
• Lazy Stored properties can’t be a constant;
for obvious reasons
• Useful when the initial values are depends
on outside factors

39. // Lazy initialization
class DataImporter {
}
class DataManager {
lazy var importer = DataImporter()
var data = [String]()
}
let m = DataManager()
// importer has not yet been created
m.data.append("Element 1");
m.data.append("Element 2");
m.data.append("Element 3");
// Initialize on first access
m.importer.import();

40. Computed Properties
computes a value
(rather than store)

41. // Computed properties
class Rectangle {
var height = 0
var width = 0
var area : Int {
get {
return height * width
}
}
}

42. Property Observers

43. // Property Observers
class Temperature {
var current : Int = 26 {
willSet {
println("(newValue)");
// Prints 32
}
didSet {
println("(oldValue)");
// Prints 26
}
}
}
var obj = Temperature()
obj.current = 32;

44. Override properties

45. Closures

46. Self-contained blocks of
functionality that can be
passed around and used in
your code.

47. Similar to blocks in
Objective-C

48. Closures
// Closures
var cities = ["New Delhi", "Trivandrum", "Kochi", "Bangalore"]
// Sort with delegates
cities.sort({ (a, b) -> Bool in
a < b
})

49. Closures - Trailing spaces
// Closures
var cities = ["New Delhi", "Trivandrum", "Kochi", "Bangalore"]
// Sort with delegates
cities.sort({ (a, b) -> Bool in
a < b
})

50. Closures - Parentheses
// Closures
var cities = ["New Delhi", "Trivandrum", "Kochi", "Bangalore"]
// Sort with delegates
cities.sort { (a, b) -> Bool in
a < b
}

51. Closures - Type inference
// Closures
var cities = ["New Delhi", "Trivandrum", "Kochi", "Bangalore"]
// Sort with delegates
cities.sort { (a, b) -> Bool in
a < b
}

52. Closures - Type inference
// Closures
var cities = ["New Delhi", "Trivandrum", "Kochi", "Bangalore"]
// Sort with delegates
cities.sort { a, b -> Bool in
a < b
}

53. Closures - Implicit return
// Closures
var cities = ["New Delhi", "Trivandrum", "Kochi", "Bangalore"]
// Sort with delegates
cities.sort { a, b in
a < b
}

54. Closures - Positional
Parameters
// Closures
var cities = ["New Delhi", "Trivandrum", "Kochi", "Bangalore"]
// Sort with delegates — Positional parameters
cities.sort { $0 < $1 }

55. Closures - Operator as
closure
// Closures
var cities = ["New Delhi", "Trivandrum", "Kochi", "Bangalore"]
// Sounds interesting?
cities.sort( < )

56. Optionals

57. represent possible
missing values

58. stack.pop?
response.parse().age?

59. // Age can be nil
var age : Int?
age = response.parse()

60. Unwrapping

61. var age : Int?
age = response.parse()
let x = age!
// Your program would crash if you unwrap a nil value

62. Optional Binding

63. class Person {
var residence : Residence?
}
class Residence {
var address : Address?
}
class Address {
var buildingNumber : String?
var streetName : String?
var apartmentNumber : String?
}

64. // Optional Binding
if let home = paul.residence {
if let postalAddress = home.address {
if let building = postalAddress.buildingNumber {
// Code
}
}
}

65. Optional Chaining

66. // Optional Chaining
let buildingNumber = paul.residence?.address?.buildingNumber

67. // optional chaining + bind + unwrap
if let buildingNumber = paul.residence?.address?.buildingNumber {
}

68. Initializer

69. Convenience &
Designated Initializers

70. designated initializers are primary
initializers of a class
a class must have at least one
designated initializer
classes tend to have few
designated initializers

71. convenience initializers
are secondary; supporting
initializers of a class

72. class Food {
var name: String
// Designated Initializer
init(name: String) {
self.name = name
}
// Convenience Initializer
convenience init() {
self.init(name: "Unnamed")
}
}

73. class Food {
var name: String
// Designated Initializer
init(name: String) {
self.name = name
}
// Convenience Initializer
convenience init() {
self.init(name: "Unnamed")
}
}

74. class Food {
var name: String
// Designated Initializer
init(name: String) {
self.name = name
}
// Convenience Initializer
convenience init() {
self.init(name: "Unnamed")
}
}

75. overriding
initializers

76. class Vehicle {
let numberOfWheels = 0
}
class Bicycle : Vehicle {
override init() {
super.init()
numberOfWheels = 2
}
}
class Car : Vehicle {
override init() {
super.init()
numberOfWheels = 4
}
}

77. class Vehicle {
let numberOfWheels = 0
}
class Bicycle : Vehicle {
override init() {
super.init()
numberOfWheels = 2
}
}
class Car : Vehicle {
override init() {
super.init()
numberOfWheels = 4
}
}

78. class Vehicle {
let numberOfWheels = 0
}
class Bicycle : Vehicle {
override init() {
super.init()
numberOfWheels = 2
}
}
class Car : Vehicle {
override init() {
super.init()
numberOfWheels = 4
}
}

79. class Vehicle {
let numberOfWheels = 0
}
class Bicycle : Vehicle {
override init() {
super.init()
numberOfWheels = 2
}
}
class Car : Vehicle {
override init() {
super.init()
numberOfWheels = 4
}
}

80. Extensions

81. helps you to attach
functionality data types; even
to the ones you didn’t create!

82. // Extension as instance method
extension Int {
func plusOne() -> Int {
return self + 1
}
}
var i = 5
i.plusOne()
10.plusOne()

83. // Extension as instance method
extension Int {
func plusOne() -> Int {
return self + 1
}
}
var i = 5
i.plusOne()
10.plusOne()

84. // Extension as instance method
extension Int {
func plusOne() -> Int {
return self + 1
}
}
var i = 5
i.plusOne()
10.plusOne()

85. // Extension as property
extension Double {
var km : Double { return self*1000.0 }
var m : Double { return self }
var cm : Double { return self / 100.0 }
var mm : Double { return self / 10000.0 }
var ft : Double { return self / 3.28084 }
}
let threeFeet = 3.ft // Meters
let oneInch = 25.4.mm // Meters

86. // Extension as property
extension Double {
var km : Double { return self*1000.0 }
var m : Double { return self }
var cm : Double { return self / 100.0 }
var mm : Double { return self / 10000.0 }
var ft : Double { return self / 3.28084 }
}
let threeFeet = 3.ft // Meters
let oneInch = 25.4.mm // Meters

87. // Extension as property
extension Double {
var km : Double { return self*1000.0 }
var m : Double { return self }
var cm : Double { return self / 100.0 }
var mm : Double { return self / 10000.0 }
var ft : Double { return self / 3.28084 }
}
let threeFeet = 3.ft // Meters
let oneInch = 25.4.mm // Meters

88. // Extension as class method
extension UIColor {
class func chilliRed() -> UIColor {
return UIColor(red: 94/255, green: 25/255, blue: 33/255,
alpha: 1)
}
}
var chilliRed = UIColor.chilliRed()

89. // Extension as class method
extension UIColor {
class func chilliRed() -> UIColor {
return UIColor(red: 94/255, green: 25/255, blue: 33/255,
alpha: 1)
}
}
var chilliRed = UIColor.chilliRed()

90. // Extension as class method
extension UIColor {
class func chilliRed() -> UIColor {
return UIColor(red: 94/255, green: 25/255, blue: 33/255,
alpha: 1)
}
}
var chilliRed = UIColor.chilliRed()

91. Protocols &
Delegates

92. Protocols are
interface definitions

93. class ViewController: UIViewController, FBLoginViewDelegate {
}

94. class ViewController: UIViewController, FBLoginViewDelegate {
}
Class

95. class ViewController: UIViewController, FBLoginViewDelegate {
}
ProtocolClass

96. protocol LoginProtocol {
func loginSuccessful()
func loginFailed()
}
class ViewController : LoginProtocol {
func loginFailed() {
// code
}
func loginSuccessful() {
// code
}
}

97. protocol LoginProtocol {
var someProperty : Int { get set }
func loginSuccessful()
func loginFailed()
}
class ViewController : LoginProtocol {
func loginFailed() {
// code
}
func loginSuccessful() {
// code
}
var someProperty : Int = 0 {
willSet {
// Update UI with newValue
}
didSet {
// code
}
}
}

98. protocol LoginProtocol {
var someProperty : Int { get set }
func loginSuccessful()
func loginFailed()
}
class ViewController : LoginProtocol {
func loginFailed() {
// code
}
func loginSuccessful() {
// code
}
var someProperty : Int = 0 {
willSet {
// Update UI with newValue
}
didSet {
// code
}
}
}

99. protocol LoginProtocol {
var someProperty : Int { get set }
func loginSuccessful()
func loginFailed()
}
class ViewController : LoginProtocol {
func loginFailed() {
// code
}
func loginSuccessful() {
// code
}
var someProperty : Int = 0 {
willSet {
// Update UI with newValue
}
didSet {
// code
}
}
}

100. protocol LoginProtocol {
var someProperty : Int { get set }
func loginSuccessful()
func loginFailed()
}
class ViewController : LoginProtocol {
func loginFailed() {
// code
}
func loginSuccessful() {
// code
}
var someProperty : Int = 0 {
willSet {
// Update UI with newValue
}
didSet {
// code
}
}
}

101. Generics

102. func swapInt(inout a:Int, inout b:Int) {
let t = a; a = b; b = t
}
func swapString(inout a:String, inout b:String) {
let t = a; a = b; b = t
}
var a = 10, b = 20
swapInt(&a, &b)
var p = "iOS 7", q = "iOS 8"
swapString(&p,&q)

103. func swapInt(inout a:Int, inout b:Int) {
let t = a; a = b; b = t
}
func swapString(inout a:String, inout b:String) {
let t = a; a = b; b = t
}
var a = 10, b = 20
swapInt(&a, &b)
var p = "iOS 7", q = "iOS 8"
swapString(&p,&q)
// MARK: With Generics
func Swap <T> (inout a: T, inout b: T) {
let t = a; a = b; b = t
}
Swap(&a, &b);
Swap(&p, &q);

104. func swapInt(inout a:Int, inout b:Int) {
let t = a; a = b; b = t
}
func swapString(inout a:String, inout b:String) {
let t = a; a = b; b = t
}
var a = 10, b = 20
swapInt(&a, &b)
var p = "iOS 7", q = "iOS 8"
swapString(&p,&q)
// MARK: With Generics
func Swap <T> (inout a: T, inout b: T) {
let t = a; a = b; b = t
}
Swap(&a, &b);
Swap(&p, &q);

105. // Generic Type
struct Stack<T> {
var items = [T]()
mutating func push(item: T) {
items.append(item)
}
mutating func pop() -> T {
return items.removeLast()
}
}

106. // Stack from somewhere
class Stack<T> {
}
// Extension
extension Stack {
func top() -> T? {
return nil
}
}

107. // Type constraints
func findIndex<T: Equatable>( array: [T], valueToFind: T) -> Int? {
for(index, value) in enumerate(array) {
if value == valueToFind {
return index
}
}
return nil
}

108. Mutating

109. Structures and enumerations are value
types.
By default, the properties of a value type
cannot be modified from within its
instance methods.

110. // Immutatbility and Mutating
struct Point {
var x = 0.0, y = 0.0
// No change in the actual object
func pointByScaling(factor: Double) -> Point {
return Point(x: self.x*factor, y: self.y*factor)
}
// Function modifies the object
mutating func scale(factor : Double) {
self.x *= factor
self.y *= factor
}
}

111. // Immutatbility and Mutating
struct Point {
var x = 0.0, y = 0.0
// No change in the actual object
func pointByScaling(factor: Double) -> Point {
return Point(x: self.x*factor, y: self.y*factor)
}
// Function modifies the object
mutating func scale(factor : Double) {
self.x *= factor
self.y *= factor
}
}

112. // Immutatbility and Mutating
struct Point {
var x = 0.0, y = 0.0
// No change in the actual object
func pointByScaling(factor: Double) -> Point {
return Point(x: self.x*factor, y: self.y*factor)
}
// Function modifies the object
mutating func scale(factor : Double) {
self.x *= factor
self.y *= factor
}
}

113. Advanced
Operators

114. struct Vector2D {
var x = 0.0, y = 0.0
}
func + (left:Vector2D, right:Vector2D) -> Vector2D {
return Vector2D(x: left.x + right.x, y: left.y + right.y)
}
// Compound Operator
func += (inout left:Vector2D, right:Vector2D) {
left.x += right.x
left.y += right.y
}
var vector = Vector2D(x: 3.0, y: 1.0)
let anotherVector = Vector2D(x: 2.0, y: 4.0)
let combinedVector = vector + anotherVector
vector += anotherVector

115. struct Vector2D {
var x = 0.0, y = 0.0
}
func + (left:Vector2D, right:Vector2D) -> Vector2D {
return Vector2D(x: left.x + right.x, y: left.y + right.y)
}
// Compound Operator
func += (inout left:Vector2D, right:Vector2D) {
left.x += right.x
left.y += right.y
}
var vector = Vector2D(x: 3.0, y: 1.0)
let anotherVector = Vector2D(x: 2.0, y: 4.0)
let combinedVector = vector + anotherVector
vector += anotherVector

116. struct Vector2D {
var x = 0.0, y = 0.0
}
func + (left:Vector2D, right:Vector2D) -> Vector2D {
return Vector2D(x: left.x + right.x, y: left.y + right.y)
}
// Compound Operator
func += (inout left:Vector2D, right:Vector2D) {
left.x += right.x
left.y += right.y
}
var vector = Vector2D(x: 3.0, y: 1.0)
let anotherVector = Vector2D(x: 2.0, y: 4.0)
let combinedVector = vector + anotherVector
vector += anotherVector

117. struct Vector2D {
var x = 0.0, y = 0.0
}
func + (left:Vector2D, right:Vector2D) -> Vector2D {
return Vector2D(x: left.x + right.x, y: left.y + right.y)
}
// Compound Operator
func += (inout left:Vector2D, right:Vector2D) {
left.x += right.x
left.y += right.y
}
var vector = Vector2D(x: 3.0, y: 1.0)
let anotherVector = Vector2D(x: 2.0, y: 4.0)
let combinedVector = vector + anotherVector
vector += anotherVector

118. struct Vector2D {
var x = 0.0, y = 0.0
}
// Custom operator - Doubling
prefix operator +++ {}
prefix func +++ (inout vector: Vector2D) ->
Vector2D {
vector += vector
return vector
}
let doubled = +++vector

119. struct Vector2D {
var x = 0.0, y = 0.0
}
// Custom operator - Doubling
prefix operator +++ {}
prefix func +++ (inout vector: Vector2D) ->
Vector2D {
vector += vector
return vector
}
let doubled = +++vector

120. struct Vector2D {
var x = 0.0, y = 0.0
}
// Custom operator - Doubling
prefix operator +++ {}
prefix func +++ (inout vector: Vector2D) ->
Vector2D {
vector += vector
return vector
}
let doubled = +++vector

121. operators are only
allowed in global
scope

122. Using Objective-C
frameworks with Swift

123. Bridging Header

125. Demo - FacebookSDK
Integration

126. References
• The Swift Programming Language - iBooks
• Using Swift with Objective-C and Cocoa -
iBooks
• WWDC 2014 Sessions on Swift
• Developing iOS 8 Apps with Swift -
iTunesU - Stanford