Sharing is Caring- Getting Started with Kotlin Multiplatform

*** Presented in KotlinConf 2019, Droidcon Singapore 2019, Droidcon Vietnam 2019 ***

As Android developers, often we work with a backend service. Often in our team, there is an iOS project or a Javascript project, with similar functionality, that is being developed by our teammate developers next door. How fun would it be to write Kotlin code once and share it with all platforms? It will save us so much time and effort in implementation and testing! Please meet Kotlin Multiplatform! It is experimental, and yet very powerful and awesome.

This session will focus on creating a full-stack Kotlin project that fits an Android app and a backend Kotlin component. You’ll learn how to share code between the components to build more efficient and robust applications. And your teammate next door will thank you as well 🙂

Transcript

1. Copenhagen Denmark SHARING IS CARING INTRO TO KOTLIN MULTIPLATFORM BRITT BARAK NEXMO, VONAGE @brittBarak
2. Copenhagen Denmark SHARING IS CARING INTRO TO KOTLIN MULTIPLATFORM BRITT BARAK NEXMO, VONAGE
3. SHARING IS CARING
4. SHARING IS CARING
5. Drinks Gift Card Cake Balloons Emma`s GoodBye @brittBarak
6. Drinks Gift Card Cake Balloons Emma`s GoodBye @brittBarak
7. Drinks Emma`s GoodBye Balloons Britt: red are the best! Gift @brittBarak
8. Drinks Emma`s GoodBye Balloons Jurgo: will go later Gift Britt: red are the best! @brittBarak
9. Drinks Emma`s GoodBye Balloons Jurgo: good? Jurgo: will go later Britt: red are the best! @brittBarak
10. Drinks Emma`s GoodBye Balloons On A Call : Jurgo & Britt Jurgo: good? Jurgo: will go later Britt: red are the best! @brittBarak
11. Data Model Conversation
12. Conversation member member member member member member member member member member Data Model
13. Conversation member member member member member member member member member Data Model member
14. Data Model Conversation Event Event Event Event Event Event Event
15. Data Model Conversation Prosecco! Call Balloons Is it good? Drinks Will go tmrw Red is best! More prosecco!
16. Emma`s GoodBye Conversation Drinks Drinks Balloons Balloons Red is best! Red is best! Will go tmrw Will go tmrw Call Call Prosecco! Prosecco! Is it good? Is it good? More prosecco! More prosecco!
17. Conversation Drinks Balloons Red is best! Will go tmrw Call Prosecco! Is it good? More prosecco! Balloons Cake Balloons Emma`s GoodBye Red is best! Will go tmrw Call Prosecco! Is it good? More prosecco! Drinks
18. Parse Sort Present OnNewEvent() @brittBarak
19. Parse Sort Present @brittBarak
20. Parse Sort Present @brittBarak
21. Parse Sort Present Present Present @brittBarak
22. Parse Sort Present Present Present Parse Sort Parse
 Sort @brittBarak
23. Parse Sort Present Present Present @brittBarak
24. @brittBarak Parse Sort Present Present Present Kotlin Multiplatform
25. @brittBarak Parse Sort Present Present Present Kotlin Multiplatform Share only what you want, when you want.
26. Parse Sort Present Present Present Kotlin Multiplatform @brittBarak
27. Common Present Present Present Kotlin Multiplatform @brittBarak
28. Common Target Target Target Kotlin Multiplatform @brittBarak
29. @brittBarak
30. @brittBarak JVM
31. @brittBarak JVM *.class
32. @brittBarak JVM *.class *.java MyClass.java
33. @brittBarak JVM *.class *.java javac MyClass.java MyClass.class
34. @brittBarak JVM *.class *.java *.kt javac
35. @brittBarak JVM *.class *.java *.kt javac MyFile.kt
36. @brittBarak JVM *.class *.java *.kt kotlinc javac MyFileKt.java MyFile.kt
37. @brittBarak JVM *.class *.java *.kt kotlinc javac MyFileKt.java MyFile.kt InnerClass.java
38. @brittBarak JVM *.class *.java *.kt kotlinc javac MyFileKt.java MyFile.kt InnerClass.java
39. @brittBarak JVM *.class *.java *.kt kotlinc javac MyFile.kt InnerClass.class MyFileKt.class
40. Common Target Target Target Kotlin Multiplatform @brittBarak
41. Common kotlin/ JVM Target Target Kotlin Multiplatform @brittBarak
42. Common kotlin/ JVM Target Target Kotlin Multiplatform Android Backend Desktop @brittBarak
43. Common kotlin/ JVM kotlin/ JS Target Kotlin Multiplatform Web browser Node.JS Android Backend Desktop @brittBarak
44. Common kotlin/ JVM kotlin/ JS kotlin/ Native Kotlin Multiplatform Web browser Node.JS Android Backend Desktop @brittBarak
45. Common kotlin/ JVM kotlin/ JS kotlin/ Native Kotlin Multiplatform Android Backend Desktop Web browser Node.JS iOS Android native Desktop native Web assembly @brittBarak
46. Get Started @brittBarak
47. 1. Add plugin plugins { id("org.jetbrains.kotlin.multiplatform").version("1.3.61") } build.gradle @brittBarak
48. 2. Set targets @brittBarak
49. Supported platforms • jvm —> Kotlin/JVM • android —> Android applications and libraries • js —> Kotlin/JS • Kotlin/Native —> @brittBarak
50. Supported platforms (Native) •androidNativeArm32 , androidNativeArm64 —> Android NDK •iosArm32, iosArm64, iosX64 —> iOS •linuxArm32Hfp, linuxMips32, linuxMipsel32, linuxX64 —> Linux •macosX64 —> MacOS •mingwX64 —> Windows •wasm32 —> WebAssembly @brittBarak
51. 2. Set targets @brittBarak
52. build.gradle plugins {…} kotlin { jvm() js("nodeJs") { … } } @brittBarak 2. Set targets
53. build.gradle plugins {…} kotlin { jvm() js("nodeJs") { … } js(“browser") { … } } @brittBarak 2. Set targets
54. For Android @brittBarak
55. build.gradle kotlin { android() } @brittBarak
56. plugins { id("org.jetbrains.kotlin.multiplatform").version("1.3.61") id(“com.android.application") // or (“com.android.library") } kotlin { android() } @brittBarak
57. plugins { id("org.jetbrains.kotlin.multiplatform").version("1.3.61") id(“com.android.application") // or (“com.android.library”) } android { ... } kotlin { android() } @brittBarak
58. 3. Source sets @brittBarak
59. 3. Source sets sourceSets { common{} android{} jvm{} } @brittBarak
60. 3. Source sets sourceSets { common{} android{} jvm{} } @brittBarak
61. 3. Source sets sourceSets { commonMain{} commonTest{} androidMain{} androidTest{} } @brittBarak
62. 3. Source sets sourceSets { commonMain { dependencies { implementation ‘org.jetbrains.kotlin:kotlin-stdlib-common’ //… } } commonTest{…} } @brittBarak
63. sourceSets { commonMain {…} commonTest{…} androidMain { dependencies { implementation "androidx.lifecycle:lifecycle-extensions:2.0.0" implementation ‘com.nexmo.android:client-sdk:1.0.0' } } androidTest {..} 3. Source sets @brittBarak
64. sourceSets { commonMain {…} commonTest{…} androidMain { dependencies { implementation 'androidx.lifecycle:lifecycle-extensions:2.0.0' implementation ‘com.nexmo.android:client-sdk:1.0.0' } } androidTest {..} 3. Source sets @brittBarak
65. Project Structure /src commonMain commonTest androidMain androidTest iosMain iosTest
66. app—> common @brittBarak
67. common: Parse Sort app: Present on New Event() @brittBarak
68. app val eventListener: NexmoEventListener = object { override fun onCustomEvent(event: NexmoEvent) { parseTextEvent(event.id, event.text, this@ListActivity) } @brittBarak
69. app val eventListener: NexmoEventListener = object { override fun onCustomEvent(event: NexmoEvent) { parseTextEvent(event.id, event.text, this@ListActivity) } @brittBarak
70. app val eventListener: NexmoEventListener = object { override fun onCustomEvent(event: NexmoEvent) { processCustomEvent(event, this@ListActivity) }
71. fun processCustomEvent(event, presenter) { } commonMain Balloon @brittBarak
72. fun processCustomEvent(event, presenter) { val customEvent = Json.nonstrict. parse(MyCustomEvent.serializer(), event) } commonMain Drinks Balloon @brittBarak
73. fun processCustomEvent(event, presenter) { val customEvent = … when (customEvent.type) { TYPE_ITEM_ADDED -> { presenter. handleItemAdded(customEvent) } } } commonMain Drinks Balloon @brittBarak
74. fun processCustomEvent(event, presenter) { val customEvent = … when (customEvent.type) { TYPE_ITEM_ADDED -> { presenter. handleItemAdded(customEvent) } } } commonMain Drinks Balloon @brittBarak
75. fun processCustomEvent(event, presenter) { val customEvent = … when (customEvent.type) { TYPE_ITEM_ADDED -> { presenter. handleItemAdded(customEvent) } } } commonMain Balloon @brittBarak Drinks
76. fun processCustomEvent(event, presenter) { val customEvent = … when (customEvent.type) { TYPE_ITEM_ADDED -> {} TYPE_TEXT -> { } } } commonMain Drinks Balloon “Hi!” @brittBarak
77. fun processCustomEvent(event, presenter) { val customEvent = … when (customEvent.type) { TYPE_ITEM_ADDED -> {} TYPE_TEXT -> { … presenter.handleNewMessage (customEvent, position) } } } commonMain Drinks Balloon @brittBarak “Hi!”
78. interface EventsPresenter { fun handleItemAdded(event: MyCustomEvent) fun handleNewMessage(event: MyCustomEvent, position: Int) } • commonMain @brittBarak
79. override fun handleNewMessage(event: MyCustomEvent, position: Int) { val itemUiModel = uiModel.items[position] itemUiModel?.events?.addItem(EventUiModel(event)) rvItems.adapter?.notifyItemChanged(position) } • app @brittBarak
80. override fun handleNewMessage(event: MyCustomEvent, position: Int) { //… recyclerview.adapter.notifyItemChanged(position) } • app @brittBarak
81. Skipping Presenter? @brittBarak
82. common —> app @brittBarak
83. expect / actual @brittBarak
84. A word about architecture @brittBarak
85. Data Domain Presentation
86. Data Domain Presentation Platform Common expect/actual DataModel UseCase UiModel View Repository
87. AddItem @brittBarak
88. Android btnAdd.setOnClickListener { //… uiModel.conversationLiveData. value?.let { it -> AddItem().execute( tilItemName.editText?.text.toString()) } } @brittBarak
89. Android btnAdd.setOnClickListener { //… uiModel.conversationLiveData. value?.let { it -> AddItem().execute( tilItemName.editText?.text.toString()) } } @brittBarak
90. Android btnAdd.setOnClickListener { //… uiModel.conversationLiveData. value?.let { it -> AddItem().execute(itemName) } } @brittBarak
91. Common/ AddItem.kt @brittBarak
92. Common/ AddItem.kt fun execute(itemName: String) { val eventJson = createEventJson(itemName) sendCustomText(eventJson) } expect fun sendCustomText(eventJson: String) @brittBarak
93. Common/ AddItem.kt fun execute(itemName: String) { val eventJson = createEventJson(itemName) sendCustomText(eventJson) } expect fun sendCustomText(eventJson: String) @brittBarak
94. Common/ AddItem.kt fun execute(itemName: String) { val eventJson = createEventJson(itemName) sendCustomText(eventJson) } expect fun sendCustomText(eventJson: String) @brittBarak
95. Common/ AddItem.kt fun execute(itemName: String) { val eventJson = createEventJson(itemName) sendCustomText(eventJson) } expect fun sendCustomText(eventJson: String) @brittBarak
96. android/ AddItem.kt actual fun sendCustomText(eventJson: String) { conversation?.sendText(eventJson, listener) } @brittBarak
97. android/ AddItem.kt actual fun sendCustomText(eventJson: String) { conversation?.sendText(eventJson, listener) } @brittBarak
98. ios/ AddItem.kt actual fun sendCustomText(eventJson: String) { activeConversation? .sendText(eventJson, completion: … //… } } @brittBarak
99. JVM/ AddItem.kt actual fun sendCustomText(eventJson: String) { coroutineScope.launch(ApplicationDispatcher) { try { nexmoApiClient.post<String> { url(pathSendEvent) body = TextContent(eventJson, ContentType.Application.Json) } // … } } @brittBarak
100. JVM/ AddItem.kt actual fun sendCustomText(eventJson: String) { coroutineScope.launch(ApplicationDispatcher) { try { nexmoApiClient.post<String> { url(pathSendEvent) body = TextContent(eventJson, ContentType.Application.Json) } // … } } @brittBarak
101. JVM/ AddItem.kt actual fun sendCustomText(eventJson: String) { coroutineScope.launch(ApplicationDispatcher) { try { nexmoApiClient.post<String> { url(pathSendEvent) body = TextContent(eventJson, ContentType.Application.Json) } // … } } @brittBarak
102. expect / actual
103. 1. Same location @brittBarak expect / actual Common/ AddItem.kt android/ AddItem.kt ios/ AddItem.kt js/ AddItem.kt
104. 1. Same location 2. Same signature @brittBarak expect / actual
105. 1. Same location 2. Same signature @brittBarak expect / actual expect fun sendCustomText(eventJson: String) actual fun sendCustomText(eventJson: String)
106. What can I use? @brittBarak
107. Packages
108. Packages
109. Libraries •KotlinX (serialsation) •Ktor (networking) •Coroutines (async) •SQKDelight (persistency) •more… • https://github.com/AAkira/Kotlin-Multiplatform-Libraries
110. KotlinConf-19 sessions Today • Kotlin Multiplatform In Action/ Alexandr Pogrebnyak - 14:00, Aud15 • Bridge The Physical World: Kotlin/Native On Raspberry Pi/ Qian Jin - 14:00, Aud12 • Your Multiplatform Kaptain Has Arrived/ Ahmed El-Helw - 15:00 , Aud12 • Shipping A Mobile Multiplatform Project On Ios & Android/ Ben Asher, Alec Strong - 16:15 Keynote • Kotlin Native Concurrency Explained/ Kevin Galligan- 17:15 , Aud12 Tomorrow: • I Walk The Line: What Parts Of An App Should Be In Kotlin Native…/Ellen Shapiro - 10:15, Aud 15 • The State Of Kotlin/Js / Sebastian Aigner - 13:00, Aud 15 • Going Native/ Ana Redmond - 14:00, Aud15 • Effective Kotlin-Swift Interoperability / John Rodriguez- 16:15 , Aud11 Hands On Labs - Preparing Your Kotlin Multiplatform Development Environment/ Big Nerd Ranch - 16:15
111. Sum up •Share what you want, when you want. •Experimental •Prepare to explore •Popular (in a good way!) •Growing, evolving, improving
112. Keep Sharing and caring
113. Keep Sharing and caring Thank you! @BrittBarak Join the goodbye party:)
114. #KotlinConf THANK YOU AND REMEMBER TO VOTE Britt Barak @brittBarak