KMP for Mobile Developers

KMP for Mobile Developers @ Droidcon Berlin 2021

Transcript

1. KMP for Mobile Developers Enrique López Mañas
2. Ego Slide • Google Developer Expert • 🇻🇳 🇩🇪 🇪🇸 • Kotlin Weekly publisher • @eenriquelopez • Mainly Android Kotlin, Backend Kotlin, iOS (mostly Swift)
3. expect fun
4. Motivation < Costs Sharing code within the company Feature teams > Quality One tech-stack
5. Multiplatform development Platform Proprietary Hybrid HTML & JavaScript Frameworks Cross-platform Native
6. Kotlin Modern language
7. Kotlin
8. Kotlin
9. Kotlin Interop
10. Kotlin Community support
11. Kotlin Top-notch tooling
12. Kotlin Sharing is optional! No life or death commitment
13. Kotlin/Anywhere Android Browser Server
14. Kotlin/Native Common JVM Native iOS framework Your iOS dev Your Android Dev JS
15. Kotlin/Native or KMP or KMM
16. KMP Sharing architecture (not UI) Shared UI is a mess
17. Kotlin/Native - Uses LLVM (5.0) - Provides runtime guarantees - Exceptions, memory management - Interop with C/Objective-C (Swift) - Platform libraries (POSIX, Apple Frameworks, Win32, DOM, etc)
18. Kotlin/Native Kotlin Compiler LLVM Kotlin Source Code (.kt) Platform Binary IR
19. The compiler -Shares Front-end with Kotlin/JVM and Kotlin/JS - Written in Java and Kotlin - Produces bitcode via LLVM API
20. Memory Management - ARC with Cycle Collector - When working pure Kotlin,don’t worry about memory management - Weak references supported - Memory sharing model - Different threads have disjoint object graphs - Object subgraphs can be transferred between threads - Immutable objects can be shared
21. Interoperatibility - Interoperatibility with C, Objective-C and Swift - Kotlin can call C/Objective-C and vice-versa - Kotlin can extend Objective-C classes and vice-versa - Memory management aware of Objective-C runtime
22. Mapping - Numbers are kept - Strings converted - Kotlin declarations wrapping C entities (functions, struct, unions, etc.) are auto- generated - Objective-C OO concepts (classes, protocols, blocks) are represented as matching Kotlin entities (classes, interfaces, lambdas) - For Objective-C, Kotlin code can be compiled to a framework
23. Mapping
24. Kotlin Library - Hold collection of code for reusability and sharing - Own format: ‘klib’ extension, which holds metadata and bitcode - Tool for creating and storing libraries in repositories
25. expect/actual
26. expect/actual
27. expect/actual
28. expect/actual JVM
29. expect/actual JS
30. expect/actual
31. expect/actual // Common expect fun randomUUID(): String // Android import java.util.* actual fun randomUUID() = UUID.randomUUID().toString() 
 
 // iOS import platform.Foundation.NSUUID actual fun randomUUID(): String = NSUUID().UUIDString()
32. Square JetBrains TouchLab Others
33. Community projects - Sqldelight - SQLiter - Multiplatform settings - Stately - OKIO2
34. Existing native libraries - Ktor - Kotlinx.Coroutines - Kotlinx.io - Atomic-fu
35. ktor - Web application framework 
 -Domain Specific Language (DSL) syntax for web apps-Kotlin coroutines for asynchronous programming 
 -Can be used on web, iOS and Android 
 -Provides a unified toolset with a single language, like Node.js but with type-safety and build-concurrency. 

36. ktor
37. ktor
38. ktor
39. ktor
40. ktor
41. ktor
42. Coroutines JetBrains async library
43. Coroutines
44. Coroutines
45. kotlinx.io Library for I/O primitives building and manipulations Experimental
46. kotlinx.io
47. kotlinx.io
48. kotlinx.io
49. AtomicFU Library for atomic operations in Kotlin
50. Considerations in state No threading primitives: synchronized, volatile Use atomic-fu instead
51. AtomicFU
52. AtomicFU
53. SQLiter •Evoution of knarch.db 
 •From Touchlab 
 •SQLiter -> SQL Driver 
 

54. SQLiter . DatabaseInstance.
55. SQLiter
56. Multiplatform settings SharedPreferences on Android and NSUserDefaults on iOS.
57. Multiplatform settings
58. kotlinx.serialization
59. Considerations in state An object belongs to one thread
60. Considerations in state Frozen objects can be shared by threads
61. Concurrency - frozen objects Everything you have written until now is not frozen
62. Considerations in state Runtime safety: KMP can verify safe mutability
63. Considerations in state - Generics
64. Considerations in state - Generics
65. Considerations in state - Generics
66. Considerations in state
67. Considerations in state Exhaustive enums
68. Considerations in state Default arguments
69. Considerations in state // Kotlin enum class LogLevel { ERROR, WARNING, INFO, DEBUG } class Logger { companion object default { fun log(level: LogLevel = LogLevel.ERROR, message: String, completion: (Boolean) -> Unit) { } } }
70. Considerations in state // Swift Logger.default.log(.error, "An error ocurred") { // Closure }
71. Considerations in state
72. Considerations in state iOS devs?
73. Architecture https://proandroiddev.com/kotlin-multiplatform-mvvm-clean-architecture-f20b99f90b95 Javier Arroyo
74. KMM Survey Q1-Q2 2021
75. KMM Survey Q1-Q2 2021
76. KMM Survey Q1-Q2 2021
77. Case studies? https://kotlinlang.org/lp/mobile/case-studies/
78. The future Hard to make predictions, easier to bet safe “I don’t know what will happen in 10 years, but there will be people asking in SO about regular expressions, and there will be another JS framework ”
79. The future @lehtimaeki
80. Recommendations - Use it with caution - Shared components - Keep versioning in mind - Do not compromise 100% of a project
81. Further resources Kotlin Slack (kotlinlang.slack.com) Touchlab resources (https://github.com/touchlab) Kotlin Weekly (http://kotlinweekly.net) K/N documentation (https://kotlinlang.org/docs/ native-overview.html)
82. Thanks!