Upgrade to Pro — share decks privately, control downloads, hide ads and more …

Kotlin For Swift Developers - Swift Paris, October 2018

Kotlin For Swift Developers - Swift Paris, October 2018

Kotlin is a new language born on the JVM that's gained a ton of popularity with Android developers. Learn about its similarities and differences with Swift, and some new, crazy things you can do with Kotlin/Native (and some totally sane things you can't do).

Sandbox app mentioned in the talk: https://github.com/designatednerd/KotlinNativeTest

Ellen Shapiro
PRO

October 24, 2018
Tweet

More Decks by Ellen Shapiro

Other Decks in Technology

Transcript

  1. KOTLIN
    FOR SWIFT DEVELOPERS
    SWIFT PARIS | PARIS, FRANCE | OCTOBER 2018
    @DESIGNATEDNERD | BAKKENBAECK.COM | JUSTHUM.COM

    View Slide

  2. KOTLIN
    POUR SWIFT DEVELOPPEURS
    SWIFT PARIS
    !
    PARIS, FRANCE OCTOBRE 2018
    @DESIGNATEDNERD
    !
    BAKKENBAECK.COM JUSTHUM.COM

    View Slide

  3. !"

    View Slide

  4. View Slide

  5. View Slide

  6. View Slide

  7. View Slide

  8. View Slide

  9. View Slide

  10. View Slide

  11. ✨ " ☕

    View Slide

  12. View Slide

  13. WHAT IS KOTLIN ?

    View Slide

  14. View Slide

  15. View Slide

  16. View Slide

  17. View Slide

  18. WHY SHOULD I CARE?

    View Slide

  19. View Slide

  20. View Slide

  21. A CONSTANT STRING

    View Slide

  22. SWIFT
    let greeting = "Hello World"

    View Slide

  23. SWIFT
    let greeting = "Hello World"
    KOTLIN
    val greeting = "Hello World"

    View Slide

  24. AN OPTIONAL INTEGER VARIABLE

    View Slide

  25. SWIFT
    var something: Int?

    View Slide

  26. SWIFT
    var something: Int?
    KOTLIN
    var something: Int?

    View Slide


  27. NullPointerException

    View Slide

  28. !"

    View Slide

  29. GENERICS
    AND
    FUNCTIONS AS PARAMETERS

    View Slide

  30. SWIFT
    func useFunction(on item: T, function: (T) -> U) -> U {
    return function(item)
    }
    func insertExclamationPoint(in string: String) -> String {
    return string
    .components(separatedBy: " ")
    .joined(separator: "! ")
    }
    let result = useFunction(on: "try Swift",
    function: insertExclamationPoint(in:))
    // result: "try! Swift"

    View Slide

  31. KOTLIN
    fun T.useFunction(action: (T) -> U): U {
    return action(this)
    }
    fun insertExclamationPoint(in: String) : String {
    return in.split(" ").joinToString("! ")
    }
    val result = "try Kotlin".useFunction { insertExclamationPoint(it) }
    // result: "try! Kotlin"

    View Slide

  32. map
    filter
    reduce

    View Slide

  33. map
    filter
    reduce*

    View Slide

  34. SWIFT
    let numbers = [ 1, 2, 3 ]
    let reduced = numbers.reduce(0, +)
    // reduced: 6

    View Slide

  35. SWIFT
    let numbers = [ 1, 2, 3 ]
    let reduced = numbers.reduce(0, +) //
    // reduced: 6

    View Slide

  36. SWIFT
    let numbers = [ 1, 2, 3 ]
    let reduced = numbers.reduce(0) { $0 + $1 }
    // reduced: 6

    View Slide

  37. SWIFT
    let numbers = [ 1, 2, 3 ]
    let reduced = numbers.reduce(20) { $0 + $1 }
    // reduced: 26

    View Slide

  38. SWIFT
    let numbers = [ 1, 2, 3 ]
    let reduced = numbers.reduce(20) { $0 + $1 }
    // reduced: 26
    KOTLIN
    val numbers = arrayOf(1, 2, 3)
    val reduced = numbers.reduce
    { total, current -> total + current }
    // reduced: 6

    View Slide

  39. SWIFT
    let numbers = [ 1, 2, 3 ]
    let reduced = numbers.reduce(20) { $0 + $1 }
    // reduced: 26

    KOTLIN
    val numbers = arrayOf(1, 2, 3)
    val reduced = numbers.reduce
    { total, current -> total + current }
    // reduced: 6

    View Slide

  40. SWIFT
    let numbers = [ 1, 2, 3 ]
    let reduced = numbers.reduce(20) { $0 + $1 }
    // reduced: 26
    KOTLIN
    val numbers = arrayOf(1, 2, 3)
    val folded = numbers.fold(20)

    { total, current -> total + current }
    // folded: 26

    View Slide

  41. SWIFT
    let doubled = [ 1, 2, 3 ].map { $0 * 2 }

    View Slide

  42. SWIFT
    let doubled = [ 1, 2, 3 ].map { $0 * 2 }
    KOTLIN
    arrayOf(1, 2, 3).map { it * 2 }

    View Slide

  43. View Slide

  44. View Slide

  45. SWIFT
    let doubled = [ 1, 2, 3 ].map { $0 * 2 }
    KOTLIN
    arrayOf(1, 2, 3).map { it * 2 }

    View Slide

  46. SWIFT
    let numbers = [ 1, 2, 3 ]
    let reduced = numbers.reduce(20) { $0 + $1 }
    // reduced: 26

    View Slide

  47. $0 $1 $2...$∞

    View Slide

  48. SWIFT
    let numbers = [ 1, 2, 3 ]
    let reduced = numbers.reduce(20) { $0 + $1 }
    // reduced: 26
    KOTLIN
    val numbers = arrayOf(1, 2, 3)
    val folded = numbers.fold(20)
    { total, current -> total + current }
    // folded: 26

    View Slide

  49. View Slide

  50. !"#

    View Slide

  51. View Slide

  52. guard

    View Slide

  53. NOW (KOTLIN)
    optionalThing?.let {
    it.doSomething()
    }

    View Slide

  54. NOW (KOTLIN)
    optionalThing?.let {
    it.doSomething()
    } else {
    doSomethingElse()
    }

    View Slide

  55. NOW (KOTLIN)
    optionalThing?.let {
    it.doSomething()
    } else { //
    !
    Not possible
    doSomethingElse()
    }

    View Slide

  56. NOW (KOTLIN)
    if (optionalThing != nil) {
    optionalThing.doSomething()
    } else {
    doSomethingElse()
    }

    View Slide

  57. NOW (KOTLIN)
    if (optionalThing != nil) {
    optionalThing.doSomething() //<- magic unwrap!!
    } else {
    doSomethingElse()
    }

    View Slide

  58. PROPOSED (KOTLIN)
    guard val thing = optionalThing else {
    return
    }
    thing.doSomething()

    View Slide

  59. apply

    View Slide

  60. NOW (SWIFT)
    UserDefaults.standard.set(true, forKey: "DefaultOne")
    UserDefaults.standard.set(false, forKey: "DefaultTwo)

    View Slide

  61. NOW (BETTER SWIFT)
    let defaults = UserDefaults.standard
    defaults.set(true, forKey: "DefaultOne")
    defaults.set(false, forKey: "DefaultTwo)

    View Slide

  62. PROPOSED (SWIFT)
    UserDefaults.standard.apply {
    "DefaultOne" = true,
    "DefaultTwo" = false,
    }

    View Slide

  63. PROTOCOLS WITH
    DEFAULT IMPLEMENTATIONS

    View Slide

  64. View Slide

  65. PROPOSED (KOTLIN)
    interface SomeInterface {
    fun doAThing()
    }

    View Slide

  66. PROPOSED (KOTLIN)
    interface SomeInterface {
    fun doAThing()
    }
    @DefaultImpl
    SomeInterface {
    fun doAThing() {
    println("Hi, I'm the default implementation!")
    }
    }

    View Slide

  67. @JVMDefault + DefaultImpl
    (SORT OF)

    View Slide

  68. SEALED CLASSES

    View Slide

  69. KOTLIN
    sealed class ViewState {
    class Empty(val placeholder: View): ViewState()
    class HasContent(val items: List): ViewState()
    }

    View Slide

  70. KOTLIN
    sealed class ViewState {
    class Empty(val placeholder: View): ViewState()
    class HasContent(val items: List): ViewState()
    }
    when (state) {
    is ViewState.Empty --> display(it.placeholder)
    is ViewState.HasContent --> adapter.reloadWith(it.items)
    }

    View Slide

  71. SWIFT
    enum TableViewState {
    case empty(placeholderView: UIView)
    case loaded(items: [Item])
    }
    switch state {
    case .empty(let placeholder):
    display(placeholder)
    case .hasContent(let items):
    dataSource.reloadWith(items)
    }

    View Slide

  72. KOTLIN
    sealed class ViewState {
    class Empty(val placeholder: View): ViewState()
    class HasContent(val items: List): ViewState()
    }

    View Slide

  73. KOTLIN
    sealed class ViewState {
    class Empty(val placeholder: View): ViewState()
    class HasContent(val items: List): ViewState() {
    val adapter = RecyclerViewAdapter(items)
    fun selectedItem(item: Item) {
    // Do something ith the selected item
    }
    }
    }

    View Slide


  74. View Slide

  75. View Slide

  76. View Slide

  77. KOTLIN / NATIVE

    View Slide

  78. View Slide

  79. PLUS ÇA CHANGE

    View Slide

  80. LLVM

    View Slide

  81. LLVM

    View Slide

  82. LLVM

    View Slide

  83. SUPPORTED PLATFORMS
    ▸ x86_64 (macOS, iOS Sim, Linux, Windows)
    ▸ arm64 (iOS, Android)
    ▸ arm32 (iOS, Android, Linux)
    ▸ arm32 hardfp (Raspberry Pi)
    ▸ MIPS (Linux)
    ▸ wasm32 (Web Assembly)

    View Slide

  84. View Slide

  85. View Slide

  86. View Slide

  87. View Slide

  88. expect fun

    View Slide

  89. View Slide

  90. View Slide

  91. View Slide

  92. KOTLIN IOS LIBRARY
    !
    WRAPPERS

    View Slide

  93. View Slide

  94. View Slide

  95. View Slide

  96. KOTLIN IOS LIBRARY
    !
    WRAPPERS*
    *(WHICH USUALLY WORK)

    View Slide

  97. KOTLIN / NATIVE
    val decoded = NSString.create(
    data = data,
    encoding = NSUTF8StringEncoding
    )

    View Slide

  98. KOTLIN / NATIVE
    val decoded = NSString.create(
    data = data,
    encoding = NSUTF8StringEncoding
    )
    // `decoded` type: NSString

    View Slide

  99. View Slide

  100. View Slide

  101. View Slide

  102. View Slide

  103. View Slide

  104. View Slide

  105. BUSINESS LOGIC

    View Slide

  106. View Slide

  107. View Slide

  108. KOTLIN / NATIVE GOTCHAS

    View Slide

  109. !

    View Slide

  110. + =

    View Slide

  111. MEMORY MANAGEMENT
    AND CONCURRENCY
    !!!!!!!

    View Slide

  112. COROUTINES

    View Slide

  113. COROUTINES*
    * ONLY WORK ON THE MAIN THREAD IN KOTLIN / NATIVE

    View Slide

  114. (˽s̕s҂˽Ɨ ˍʓˍ

    View Slide

  115. Worker

    View Slide

  116. !
    MONOREPO

    View Slide

  117. https://github.com/designatednerd/
    KotlinNativeTest

    View Slide

  118. OBJ-C INTEROP HILARITY

    View Slide

  119. SWIFT: ENUMS
    enum Things {
    case monday
    case tuesday
    case wednesday
    case thursday
    case friday
    case saturday
    case sunday
    }

    View Slide

  120. KOTLIN: ENUM CLASSES
    enum class DayOfWeek {
    Monday,
    Tuesday,
    Wednesday,
    Thursday,
    Friday,
    Saturday,
    Sunday;
    }

    View Slide

  121. View Slide

  122. A KOTLIN ENUM CLASS IN A KOTLIN / NATIVE FRAMEWORK

    View Slide

  123. A KOTLIN ENUM CLASS IN A KOTLIN / NATIVE FRAMEWORK

    View Slide

  124. A KOTLIN ENUM CLASS IN A KOTLIN / NATIVE FRAMEWORK

    View Slide

  125. SWIFT SWITCHING ON A KOTLIN ENUM
    switch day {
    case .monday:
    print("You can fall apart")
    case .tuesday,
    .wednesday:
    print("Break my heart")
    case .thursday:
    print("Doesn't even start")
    case .friday:
    print("I'm in love")
    case .saturday:
    print("Wait")
    case .sunday:
    print("Always comes too late")
    }
    //
    !
    Seems legit...

    View Slide

  126. SWIFT SWITCHING ON A KOTLIN ENUM
    switch day {
    case .monday:
    print("You can fall apart")
    case .tuesday,
    .wednesday:
    print("Break my heart")
    case .thursday:
    print("Doesn't even start")
    case .friday:
    print("I'm in love")
    case .saturday:
    print("Wait")
    case .sunday:
    print("Always comes too late")
    }
    //
    !
    ERROR:
    !
    Switch must be exhaustive

    View Slide

  127. SWIFT SWITCHING ON A KOTLIN ENUM
    switch day {
    case .monday:
    print("You can fall apart")
    case .tuesday,
    .wednesday:
    print("Break my heart")
    case .thursday:
    print("Doesn't even start")
    case .friday:
    print("I'm in love")
    case .saturday:
    print("Wait")
    case .sunday:
    print("Always comes too late")
    default:
    fatalError("Not a day") //
    !
    }

    View Slide

  128. DOCUMENTATION

    View Slide

  129. DOCUMENTATION?
    ¯\_(ϑ)_/¯

    View Slide

  130. View Slide

  131. PRODUCTION?!

    View Slide

  132. KOTLIN:

    OR
    "
    =

    View Slide

  133. try? kotlin

    View Slide

  134. https://try.kotlinlang.org

    View Slide

  135. View Slide

  136. View Slide

  137. EDU TOOLS
    PLUGIN FOR INTELLIJ OR ANDROID STUDIO

    View Slide

  138. View Slide

  139. View Slide

  140. OBLIGATORY SUMMARY SLIDE

    View Slide

  141. OBLIGATORY SUMMARY SLIDE
    ▸ Literally put the fun in functional programming

    View Slide

  142. OBLIGATORY SUMMARY SLIDE
    ▸ Literally put the fun in functional programming
    ▸ Make Friends With Android

    View Slide

  143. OBLIGATORY SUMMARY SLIDE
    ▸ Literally put the fun in functional programming
    ▸ Make Friends With Android
    ▸ Kotlin Native Could Be A Whole New World

    View Slide

  144. OBLIGATORY SUMMARY SLIDE
    ▸ Literally put the fun in functional programming
    ▸ Make Friends With Android
    ▸ Kotlin Native Could Be A Whole New World
    ▸ try! Kotlin

    View Slide

  145. ONE MORE THING

    View Slide

  146. ONE MORE THING:
    (A SHAMELESS PLUG!)

    View Slide

  147. View Slide

  148. !
    MERÇI!

    View Slide

  149. LINKS!
    ▸ Kotlin Home & Documentation: https://kotlinlang.org
    ▸ Kotlin Native MultiplatformApp tutorial
    https://kotlinlang.org/docs/tutorials/
    native/mpp-ios-android.html
    ▸ KotlinConf iOS App in Kotlin/Native:
    https://github.com/JetBrains/kotlinconf-
    app/tree/master/konfios

    View Slide

  150. MORE LINKS!
    ▸ The Edu Tools Plugin for IntelliJ or Android Studio
    https://kotlinlang.org/docs/tutorials/
    edu-tools-learner.html
    ▸ Representing State (KotlinConf talk on Sealed Classes)
    https://www.youtube.com/watch?v=-
    lVVfxsRjcY
    ▸ Sealed Classes Opened My Mind (KotlinConf Talk)
    https://www.youtube.com/watch?
    v=uGMm3StjqLI

    View Slide

  151. SHAMELESS SELF-PROMOTION!
    ▸ My talk on Protocol-Oriented Programming from Dot Swift
    https://www.dotconferences.com/2018/01/
    ellen-shapiro-protocols-all-the-way-down
    ▸ Kotlin Apprentice
    https://store.raywenderlich.com/products/
    kotlin-apprentice
    ▸ Android Apprentice
    https://store.raywenderlich.com/products/
    android-apprentice

    View Slide

  152. ILLUSTRATION CREDITS
    ▸ Monica Komperda, Native Code Forever
    (Hire her! She's awesome!)
    http://mokomperda.com/design

    View Slide