Shared Cross-Platform Modules with Kotlin/Native

Transcript

2. Shared Cross-Platform Modules with Kotlin/Native
3. Simone @viteinfinite
8. Shareholders
9. You
10. Solution Cross-Platform
11. Main platforms: • Xamarin • PhoneGap / Cordova • AppCelerator Titanium • React Native • RubyMotion • Flash • ...
20. JVM
22. Object-Oriented with bits of Functional Programming
23. Statically typed
24. Optionals var a: String = "abc" a = null // compilation error Smart casting fun demo(x: Any) { if (x is String) { print(x.length) // x is automatically cast to String } }
25. Function extensions fun MutableList<Int>.swap(index1: Int, index2: Int) { val tmp = this[index1] // 'this' corresponds to the list this[index1] = this[index2] this[index2] = tmp } val l = mutableListOf(1, 2, 3) l.swap(0, 2)
26. Lambda & Inlines max(strings, { a, b -> a.length < b.length }) Data classes data class User(val name: String, val age: Int)
27. 20% of Android apps use Kotlin1 1 https://realm.io/realm-report/
28. Server-Side
29. Kotlin/JS Transpilation to JavaScript
30. April 2017
31. Kotlin/Native
33. Konan Kotlin Native Backend
34. How it works
37. Supported Targets 1. Android Native 2. Web Assembly 3. Linux 4. macOS 5. iOS
38. Interoperable Can make use of C / C++ / Objective-C libraries
39. Can I write an entire iOS app in Kotlin?
40. YES
41. https://github.com/JetBrains/kotlinconf-app/tree/master/ios
42. But There's More
43. iOS Frameworks
44. Share a Cross-Platform Module between Android and iOS
45. Why Does it Make Sense? 1. Plug into existing codebases 2. Xcode is still the most suitable IDE for iOS 3. Code for views cannot be shared anyway 4. Either way, you have to master UIKit
46. My Use Case Written in Markdown, presented with Deckset
47. My Goal Create viewer apps, sharing parsing logic: • iOS (view logic in Swift) • Android (view logic in Kotlin) • Shared parsing library: • iOS ➡ .framework (Kotlin/Native) • Android ➡ .aar (Kotlin/JVM)
48. Project Setup
49. Project Setup !"" android/ !"" ios/ #"" common/ !"" build.gradle !"" gradle/ #"" slideparser/ !"" build.gradle #"" src/
51. common/slideparser/build.gradle !"" android/ !"" ios/ #"" common/ !"" build.gradle !"" gradle/ #"" slideparser/ !"" build.gradle ⬅⬅⬅ #"" src/
52. common/slideparser/build.gradle (1/3) buildscript { dependencies { classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version" } } repositories { mavenCentral() } apply plugin: 'konan' apply plugin: 'com.android.library' apply plugin: 'kotlin-android' // ...
53. common/slideparser/build.gradle (2/3) Android android { compileSdkVersion 26 defaultConfig { // ... } sourceSets { main.java.srcDirs += 'src/main/kotlin' main.java.srcDirs += 'src/test/kotlin' } }
54. common/slideparser/build.gradle (3/3) iOS konanArtifacts { framework('KotlinSlideParser', targets: ['iphone', 'iphone_sim']) { srcDir 'src/main/kotlin' } }
55. Tasks ./gradlew tasks assemble - Assembles all variants of all applications and packages. build - Assembles and tests this project. compileKonanKotlinSlideParserIphone - Build the Kotlin/Native framework \ 'compileKonanKotlinSlideParserIphone' for target 'IPHONE' compileKonanKotlinSlideParserIphone_sim - Build the Kotlin/Native framework 'compileKonanKotlinSlideParserIphone_sim' for target 'IPHONE_SIM'
56. Build ./gradlew -p . compileKonanKotlinSlideParserIphone
57. Multiplatform3 • A new project structure (Kotlin 1.2) • Allows to compile the same code to multiple targets: • JVM • JS • Native • Powerful DSL to define dependencies Coming in Kotlin/Native 0.6 3 https://kotlinlang.org/docs/reference/multiplatform.html
58. IDE
61. Digging Deeper
62. Digging Deeper Testing
63. Testing • Unit tests supported in Kotlin/Native • But you can use JUnit (or Spek) too • Optimal IDE support
64. Digging Deeper Objective-C Headers
65. Objective-C Generated Headers
66. Objective-C Generated Headers !"" KotlinSlideParser.framework #"" Headers $ !"" KotlinSlideParser.h ⬅⬅⬅ #"" Info.plist #"" KotlinSlideParser !"" Modules !"" module.modulemap
67. #import <Foundation/Foundation.h> @class KSPSupport, KSPMyEnum, KSPStdlibEnum, KSPOtherEnum, KSPSlideEntity, KSPSlideEntityPage, KSPMarkdownEntity, KSPMarkdownEntityItalic, KSPMarkdownEntityBold; @class KSPMarkdownEntityHeader, KSPMarkdownEntityInlineCode, KSPMarkdownEntityCodeBlock, KSPMarkdownEntityLinks; @class KSPMarkdownEntityPlain, KSPMarkdownEntityRefer, KSPMarkdownEntityDelete, KSPSlideParser; @protocol KSPStdlibComparable; NS_ASSUME_NONNULL_BEGIN @interface KotlinBase : NSObject -(instancetype) init __attribute__((unavailable)); +(instancetype) new __attribute__((unavailable)); +(void)initialize __attribute__((objc_requires_super)); @end; @interface KotlinBase (KotlinBaseCopying) <NSCopying> @end; __attribute__((objc_runtime_name("KotlinMutableSet"))) @interface KSPMutableSet<ObjectType> : NSMutableSet<ObjectType> @end; __attribute__((objc_runtime_name("KotlinMutableDictionary"))) @interface KSPMutableDictionary<KeyType, ObjectType> : NSMutableDictionary<KeyType, ObjectType> @end; __attribute__((objc_subclassing_restricted)) @interface KSPSupport : KotlinBase -(instancetype)init NS_SWIFT_NAME(init()) NS_DESIGNATED_INITIALIZER; -(NSNumber* _Nullable)optionalInt NS_SWIFT_NAME(optionalInt()); -(void)somethingThatThrows NS_SWIFT_NAME(somethingThatThrows()); @end; @protocol KSPStdlibComparable @required -(int32_t)compareToOther:(id _Nullable)other NS_SWIFT_NAME(compareTo(other:)); @end; NS_ASSUME_NONNULL_END
68. Kotlin / ObjC / Swift Type Mapping Kotlin Objective-C Swift Boolean BOOL Bool Float / Double float / double Float / Double Int int32_t Int32 String NSString * String Array<String> StdlibArray * StdlibArray List<String> 2 NSArray<NSString *> * [String] Int? Nullable NSNumber * NSNumber? 2 From 0.6
69. Kotlin Objective-C Swift interface protocol protocol class class class data class class class enum class StdlibEnum StdlibEnum Kotlin Objective-C Swift open (subclassable) open public (subclassable) open
70. Digging Deeper Debugging
71. Debugging • Debugging is supported • Compiler produces a .dSYM file • "official" LLVM symbolication file for debugging • DWARF format • Allows using Xcode for debugging
72. Debugging (lldb) breakpoint set --func-regex "myFunc" (lldb) b kfun:
74. Digging Deeper Memory Management
75. Memory Management • ARC-based... • ...with an automatic cycle collector on top • Garbage Collection is performed periodically • No weak / unowned references
76. Digging Deeper Exceptions
77. Exceptions • All exceptions are unchecked in Kotlin • @Throws is not supported in Kotlin/Native • Cannot bridge Kotlin Exceptions to Swift Errors
78. Exception (un)Handling fun somethingThatThrows() { throw Exception(message = "Oops.") } ‑ Uncaught Kotlin exception: kotlin.Exception: Oops. at 3 KotlinSlideParser 0x104cb54f3 kfun:kotlin.Exception.<init>(kotlin.String)kotlin.Exception + 115 at 4 KotlinSlideParser 0x104c81dea kfun:fr.xebia.slideparser.Support.somethingThatThrows() + 122 at 5 KotlinSlideParser 0x104c81d10 KotlinSlideParser + 7440 at 6 SlideRehearser 0x104978081 _T014SlideRehearser14ViewControllerC11viewDidLoadyyF + 81 at 7 SlideRehearser 0x104978104 _T014SlideRehearser14ViewControllerC11viewDidLoadyyFTo + 36 at 8 UIKit 0x107e8646c -[UIViewController loadViewIfRequired] + 1235 ...
80. Digging Deeper Concurrency
81. Concurrency Kotlin/Native supports: • Workers (specific to Kotlin/Native) • Coroutines (as in Kotlin/JVM) • not particularly developer-friendly in K/N • high-level API (kotlinx.coroutines) not yet available
82. In Action!
83. Kotlin public sealed class SlideEntity { data class Page(val contents: List<MarkdownEntity>): SlideEntity() } public sealed class MarkdownEntity { data class Header(val contents: List<MarkdownEntity>, val level: Int): MarkdownEntity() data class Plain(val contents: String): MarkdownEntity() } public class SlideParser { public fun parsePages(string: String): List<SlideEntity>? { val result = this.pageParser().process(string) return if (result.isEmpty()) { null } else { result[0].first } } }
84. iOS (Swift) import KotlinSlideParser // ... let parser = KSPSlideParser() guard let pages = parser.parsePages(string: myText) else { return } pages.first?.contents.forEach { entity in switch entity { case let header as KSPMarkdownEntityHeader: header.level // Level of the header case let plain as KSPMarkdownEntityPlain: plain.contents // Text of the entity default: break } }
85. Android (Kotlin) import fr.xebia.slideparser.SlideParser // ... val parser = SlideParser() val pages = parser.parsePages(myText) pages?.first()?.contents?.forEach { when(it) { is MarkdownEntity.Header -> it.level // Level of the header is MarkdownEntity.Plain -> it.contents // Text of the entity } }
87. Another Approach
88. Another Approach On Android, we can compile to an NDK Library • less developer-friendly • better performance • suitable for CPU-intensive operations
89. Current Limitations
90. Current Limitations • Still a Technology Preview • Compilation time • A number of known issues • Some everyday functions not available in K/N • Some types poorly translate to Swift (e.g. generics) • iOS bitcode not supported • ENABLE_BITCODE needs to be set to NO
91. Future Evolutions
92. Future Evolutions • Multiplatform • a specific DSL to build cross-platform apps • AppCode Support • Better Objective-C header generation • kotlinx.coroutines extensions • Native interoperability with Swift (?) • And more...
93. Other Resources • Swift is like Kotlin • Anything you can do, I can do better • Kotlin Blog • Deep Dive into Kotlin/Native by Andrey Breslav • Kotlin Slack
94. Summing Up
95. Main strengths • Reuse Kotlin code you already have • "Feels" like Swift • Write once, run anywhere - even without the JVM! • Battle-tested, mobile-first IDEs
96. Kotlin/Native is still young but already usable, and very, very promising
97. Thank You!
98. Simone @viteinfinite
99. FrenchKit September, 20-21 • Paris frenchkit.fr
100. Source code available here: github.com/viteinfinite/KotlinSlideParser