I Walk The Line - What Should Be Kotlin/Native And What (Maybe) Shouldn't - KotlinConf, Copenhagen, Denmark, December 2019

Code:
https://github.com/bakkenbaeck/PorchPirateProtector

Abstract:
Kotlin/Native is an incredibly powerful toolset for creating cross-platform code, particularly for mobile apps. But iOS and Android both have their...quirks, particularly around handling Application, View Controller, and Fragment/Activity lifecycle. The line between getting things done more efficiently and getting sucked into a whirlpool of memory leaks can seem mighty thin, but it can be walked. In this talk, Ellen will discuss how she's walked it, what's worked -- and what definitely has not.

Transcript

1. I WALK THE LINE WHAT SHOULD BE KOTLIN/NATIVE, AND WHAT (MAYBE) SHOULDN'T KOTLINCONF | COPENHAGEN, DENMARK | DECEMBER 2019 ELLEN SHAPIRO | @DESIGNATEDNERD | APOLLOGRAPHQL.COM
7. !
9. EVERYONE HAS A CROSS-PLATFORM ! HORROR STORY
10. ! AIRBNB : REACT NATIVE
13. JAVASCRIIIIIIIIPT!
20. ! DROPBOX C++
24. DE-PRIORITIZE DEVELOPER EXPERIENCE AT YOUR OWN RISK
25. DEVS WHO HAVE WORKED IN SAFER LANGUAGES REFUSE TO GO BACK
27. ! SHAMELESS PLUG ALERT!
39. KOTLIN/NATIVE FOCUSES ON SHARING LOGIC
40. CENTRALIZE TESTING
43. !
45. USE KOTLIN/NATIVE FOR ALL THE THINGS!
46. ! PORCH PIRATE PROTECTOR https://github.com/bakkenbaeck/porchpirateprotector
49. iOS app
50. iOS app Android app
51. iOS app Android App Server
52. iOS app Android app Server Raspberry pi
53. Works With Kotlin? iOS app Android app Server Raspberry pi
54. Works With Kotlin? iOS app ✅ Android app ✅ Server ✅ Raspberry pi ✅
55. Works With Kotlin? iOS app ✅ Android app ✅ Server ✅ Raspberry pi* ✅ * - soon, I hope
58. MVA*
59. MVA* * - ANYTHING OTHER THAN A MODEL OR A VIEW FOR THE LOVE OF GOD
60. MVP
63. MODEL: VIEW: PRESENTER:
64. MODEL: data class VIEW: PRESENTER:
65. MODEL: data class VIEW: interface PRESENTER:
66. MODEL: data class VIEW: interface PRESENTER: class
67. VIEW: interface
68. IOS VIEW: UIViewController ANDROID VIEW: TESTING VIEW:
69. IOS VIEW: UIViewController ANDROID VIEW: Fragment* TESTING VIEW:
70. IOS VIEW: UIViewController ANDROID VIEW: Fragment* TESTING VIEW: *May not apply if your name is jake wharton
71. IOS VIEW: UIViewController ANDROID VIEW: Fragment* TESTING VIEW: ¯\_(ϑ)_/¯ *May not apply if your name is jake wharton
73. commonMain PRESENTER class DeviceDetailPresenter( val view: DeviceDetailView, val device: PairedDevice, storage: SecureStorage ): BaseCoroutinePresenter(secureStorage = storage) { // ... }
74. commonMain VIEW interface DeviceDetailView: IndefiniteLoadingIndicating { fun setTitle(toString: String) fun setLockButtonEnabled(enabled: Boolean) fun setUnlockButtonEnabled(enabled: Boolean) fun setApiError(toString: String?) }
75. ANDROID APP FRAGMENT class DeviceDetailFragment: Fragment(), DeviceDetailView { private val presenter by lazy { DeviceDetailPresenter( this, currentDevice, KeyStoreManager(this.context!!) ) } //... }
76. WHAT HAVE I DONE WRONG HERE? class DeviceDetailFragment: Fragment(), DeviceDetailView { private val presenter by lazy { DeviceDetailPresenter( this, currentDevice, KeyStoreManager(this.context!!) ) } //... }
77. WHAT HAVE I DONE WRONG HERE? class DeviceDetailFragment: Fragment(), DeviceDetailView { private val presenter by lazy { DeviceDetailPresenter( this, currentDevice, KeyStoreManager(this.context!!) ) } //... }
78. PRESENTER class DeviceDetailPresenter( val view: DeviceDetailView, val device: PairedDevice, storage: SecureStorage ): BaseCoroutinePresenter(secureStorage = storage) { // ... }
82. (Copyright Alex Norris of Webcomic Name)
83. MVP
84. MVSP
85. MVSP MODEL VIEWSTATE PRESENTER
86. VIEW INTERFACES -> VIEWSTATE OBJECTS
87. class DeviceDetailPresenter( val device: PairedDevice ): BaseCoroutinePresenter() { data class DeviceDetailViewState( val lockButtonEnabled: Boolean, val unlockButtonEnabled: Boolean, val errorMessage: String? = null, val indicatorAnimating: Boolean = false ) // ... }
88. suspend fun getStatusAsync( initialViewStateHandler: (DeviceDetailViewState) -> Unit, secureStorage: SecureStorage ): DeviceDetailViewState { // ... } suspend fun lockAsync( initialViewStateHandler: (DeviceDetailViewState) -> Unit, secureStorage: SecureStorage ): DeviceDetailViewState { //... } suspend fun unlockAsync( initialViewStateHandler: (DeviceDetailViewState) -> Unit, secureStorage: SecureStorage ): DeviceDetailViewState { //.. }
89. suspend fun getStatusAsync( initialViewStateHandler: (DeviceDetailViewState) -> Unit, secureStorage: SecureStorage ): DeviceDetailViewState { // ... } suspend fun lockAsync( initialViewStateHandler: (DeviceDetailViewState) -> Unit, secureStorage: SecureStorage ): DeviceDetailViewState { //... } suspend fun unlockAsync( initialViewStateHandler: (DeviceDetailViewState) -> Unit, secureStorage: SecureStorage ): DeviceDetailViewState { //.. }
90. suspend fun getStatusAsync( initialViewStateHandler: (DeviceDetailViewState) -> Unit, secureStorage: SecureStorage ): DeviceDetailViewState { // ... } suspend fun lockAsync( initialViewStateHandler: (DeviceDetailViewState) -> Unit, secureStorage: SecureStorage ): DeviceDetailViewState { //... } suspend fun unlockAsync( initialViewStateHandler: (DeviceDetailViewState) -> Unit, secureStorage: SecureStorage ): DeviceDetailViewState { //.. }
91. UNIDIRECTIONAL ♻ DATA FLOW
92. BLAME SWIFTUI
93. DESTROY YOUR HEROES UI STATE
95. import SwiftUI struct ValueView: View { var value: Double = 0 var body: some View { return Text("\(value)") } }
96. import SwiftUI struct ValueView: View { var value: Double = 0 var body: some View { return Text("\(value)") } }
97. import SwiftUI struct ValueView: View { var value: Double = 0 var body: some View { return Text("\(value)") } }
98. LESS MUTABLE STATE -> FEWER PROBLEMS
99. SHARING MAKES SENSE THEORETICALLY
100. STYLE DEFINITION
101. COLORS
102. val colorPrimary = "#05C1FD" val colorPrimaryDark = "#5848F4" val colorAccent = "#fb5502" val colorAccentSelected = "#c94402" val textLight = "#ffffff" val textMiddle = "#777777" val textDark = "#000000" val errorRed = "#cc0000" val success = "#0d9b2a"
103. enum class PPPColor(val hexColor: String) { ColorPrimary("#05C1FD"), ColorPrimaryDark("#5848F4"), ColorAccent("#fb5502"), ColorAccentSelected("#c94402"), TextLight("#ffffff"), TextMiddle("#777777"), TextDark("#000000"), ErrorRed("#cc0000"), Success("#0d9b2a"); val red: Long get() = hexColor.substring(1, 3).toLong(16) val green: Long get() = hexColor.substring(3, 5).toLong(16) val blue: Long get() = hexColor.substring(5, 7).toLong(16) }
104. enum class PPPColor(val hexColor: String) { ColorPrimary("#05C1FD"), ColorPrimaryDark("#5848F4"), ColorAccent("#fb5502"), ColorAccentSelected("#c94402"), TextLight("#ffffff"), TextMiddle("#777777"), TextDark("#000000"), ErrorRed("#cc0000"), Success("#0d9b2a"); val red: Long get() = hexColor.substring(1, 3).toLong(16) val green: Long get() = hexColor.substring(3, 5).toLong(16) val blue: Long get() = hexColor.substring(5, 7).toLong(16) }
105. import platform.UIKit.UIColor fun PPPColor.toUIColor(): UIColor { return UIColor( red = this.red.toDouble() / 255.0f, green = this.green.toDouble() / 255.0f, blue = this.blue.toDouble() / 255.0f, alpha = 1.0 ) }
106. import android.graphics.Color import no.bakkenbaeck.pppshared.ui.PPPColor fun PPPColor.toAndroidColor(): Int { return Color.parseColor(this.hexColor) }
108. SHOULD YOU SHARE CODE OR SOMETHING ELSE?
118. ! LIBRARIES
119. ktor + kotlinx.serialization
120. NETWORK + PARSING
121. NETWORK + PARSING IOS + ANDROID + SERVER
122. @Serializable data class LockState( val deviceId: Int, val isLocked: Boolean )
123. KTOR USES SINGLE-THREADED COROUTINES
126. DIG IN TO FIND OUT WHERE LIBRARIES ARE KINDA CHEATING
128. DATABASE SQLDelight
129. PRO: ONE DATABASE TO ! RULE THEM ALL
130. CON: GIVE UP DEEP INTEGRATION OF CoreData AND Room
131. (HOW BAD IS THAT, REALLY?)
132. ANDROID: SQLDELIGHT FLOW EXTENSIONS
135. IOS: SWIFTUI
136. KNOW WHY YOU'RE USING KOTLIN/NATIVE
140. via http://www.dorkly.com/post/67855/watch-someone-beat-all-4-original-mario-games-at-the-same-time
142. CROSS-PLATFORM IS NOT AN EXCUSE TO IGNORE THE PLATFORM
143. WHAT AM I GIVING UP THAT THE SYSTEM HAS BEEN DOING FOR ME?
144. IS IT WORTH THAT TRADE-OFF?
145. OBLIGATORY SUMMARY SLIDE
146. OBLIGATORY SUMMARY SLIDE > Kotlin/Native can be a double-edged sword
147. OBLIGATORY SUMMARY SLIDE > Kotlin/Native can be a double-edged sword > You can move way faster on some things
148. OBLIGATORY SUMMARY SLIDE > Kotlin/Native can be a double-edged sword > You can move way faster on some things > Be mindful of the trade-offs you're making
149. OBLIGATORY SUMMARY SLIDE > Kotlin/Native can be a double-edged sword > You can move way faster on some things > Be mindful of the trade-offs you're making > Prioritize developer experience to drive adoption
150. OBLIGATORY SUMMARY SLIDE > Kotlin/Native can be a double-edged sword > You can move way faster on some things > Be mindful of the trade-offs you're making > Prioritize developer experience to drive adoption > Remember why you're using K/N in the first place
151. LINKS! > The (not so) hidden cost of sharing code between iOS and Android https://blogs.dropbox.com/tech/2019/08/ the-not-so-hidden-cost-of-sharing-code- between-ios-and-android/ > React Native at AirBnB https://medium.com/airbnb-engineering/ react-native-at-airbnb-f95aa460be1c