Cross-Platform Modules with Kotlin/Native (v. 2018.10)

Transcript

1. Shared Cross-Platform Modules with Kotlin
2. Simone @viteinfinite
4. Microsoft Surface
8. 1.
10. 2.
13. ❝"A Surface app is like an iPad app"❞
16. Until...
19. ❝"An iPad app is like a Xoom app"❞
20. Right?
21. WRONG.
22. WRONG.
23. WRONG.
25. Cross-Platform
26. Cross-Platform
27. Cross-Platform Cross-Platform Cross-Platform
28. Cross-Platform Cross-Platform Cross-Platform Cross-Platform Cross-Platform Cross-Platform Cross-Platform Cross-Platform Cross-Platform Cross-Platform Cross-Platform Cross-Platform Cross-Platform Cross-Platform Cross-Platform Cross-Platform Cross-Platform Cross-Platform Cross-Platform Cross-Platform Cross-Platform Cross-Platform Cross-Platform Cross-Platform
33. Years Later...
45. Konan
46. Konan Kotlin Native Backend
48. Server-Side
49. Kotlin for JavaScript Transpilation to JavaScript
51. ❝"Kotlin is like Swift"❞
54. How It Works
57. ❝A Kotlin/Native compiler is like a Swift compiler❞
59. Supported Targets ➀ Android Native ➁ Web Assembly ➂ Linux ➃ Embedded Systems ➄ macOS ➅ iOS
60. Interoperable Can make use of C / C++ / Objective-C libraries
62. Can I Write an Entire iOS App in Kotlin?
63. YES
64. https://github.com/JetBrains/kotlinconf-app/tree/master/ios
65. Can I Write a Complete Cross-Platform App in Kotlin?
66. Can I Write a Complete Cross-Platform App in Kotlin?
67. NO.
69. But...
70. iOS Frameworks
71. Share a Cross-Platform Module Between Android and iOS
72. Let's Try Out
73. My Use Case Written in Markdown, presented with Deckset
74. My Goal Create viewer apps, sharing parsing logic: ☞ Shared parsing library: ☞ iOS ➡ .framework (Kotlin/Native) ☞ Android ➡ .aar (Kotlin/JVM) ☞ iOS (view logic in Swift) ☞ Android (view logic in Kotlin)
75. Multiplatform Since Kotlin 1.2, Kotlin/Native 0.6
76. Multiplatform ☞ Sharing code across multiple platforms: ☞ JVM ☞ JS ☞ Native (iOS, macOS, Android Native, ...)
78. Kotlin 1.3
79. Kotlin 1.3 New Multiplatform DSL
80. Kotlin 1.3 New Multiplatform DSL Key Concepts
81. Kotlin Gradle Extension > build.gradle kotlin { // ... }
82. 4 Key Concepts ➀ SourceSet ➁ Target ➂ Preset ➃ Compilation
83. 1. SourceSet ☞ A group of source files ☞ Usually what's inside the src/<XXX> folder
84. 1. SourceSet ☞ A group of source files ☞ Usually what's inside the src/<XXX> folder ├── build.gradle │ └── src │ ├── main // ← SourceSet │ ├── iosMain // ← SourceSet │ └── ... // ← Other SourceSets
85. 2. Target ☞ A variant of your project for a given platform (e.g. Android, iOS device, iOS simulator, Linux, etc) kotlin { targets { // ... } }
86. 3. Preset ☞ A way to easily create a target ☞ It's composed of pre-defined configuration kotlin { targets { fromPreset(presets.iosX64, 'iosSim') } }
87. 4. Compilation ☞ A "trasformation" of your sources for a specific target ☞ Each target can have one or more compilation, for instance "main", "test", etc
88. 4. Compilation kotlin { targets { fromPreset(presets.iosX64, 'iosSim') { compilations.main.foo = bar } } }
89. Target+Compilation ☞ Kotlin automatically creates a sourceSet for each possible compilation + target combination
90. Target+Compilation ☞ Kotlin automatically creates a sourceSet for each possible compilation + target combination ├── build.gradle │ └── src │ ├── main // almost useless in MPP │ ├── commonMain // created automatically │ ├── iosMain │ ├── iosTest │ └── ...
91. What if...
92. ...you need a platform-specific implementation? class Service { fun log() { // Platform-specific code // NSLog on iOS // Log.d on Android } }
93. 2 Solutions
94. 1. Interfaces Interfaces get translated conveniently across platforms interface Logger { fun log(string: String) } class Service(val logger: Logger) { fun log(string: String) { logger.log(string) } }
95. 2. Actuals: 1/3 Actuals are a functionality introduced in KMPP 1.2 // SourceSet commonMain expect class Logger { fun log(string: String) } class Service(val logger: Logger) { fun log(string: String) { logger.log(string) } }
96. 2. Actuals: 2/3 // SourceSet iosMain actual class Logger { actual fun log(string: String) { NSLog(string) } }
97. 2. Actuals: 3/3 kotlin { sourceSets { iosMain { dependsOn commonMain } } ...
98. Project Setup
99. Project Setup ├── build.gradle │ └── src │ ├── commonMain │ ├── iosMain │ └── main
101. build.gradle: 1/4 buildscript { ext.kotlin_version = '1.3.0-rc-57' // ... Repositories and dependencies as usual } apply plugin: 'kotlin-multiplatform' // ...
102. build.gradle: 2/4 apply plugin: 'com.android.library' android { compileSdkVersion 26 defaultConfig { minSdkVersion 21 targetSdkVersion 26 versionCode 1 versionName '1.0' } }
103. build.gradle: 3/4 kotlin { sourceSets { iosMain { dependsOn commonMain } }
104. build.gradle: 4/4 targets { fromPreset(presets.android, 'androidLibrary') def isSim = findProperty("kotlin.target") == "iosSim" def iosPreset = isSim ? presets.iosX64 : presets.iosArm64 fromPreset(iosPreset, 'iosSim') { compilations.main.outputKinds('FRAMEWORK') } } }
105. Tasks ./gradlew tasks assemble - Assembles all variants of all applications and packages. build - Assembles and tests this project. linkDebugFrameworkIos - Links an Objective-C framework from the 'main' compilation for target 'native'.
106. Build ./gradlew -p . linkDebugFrameworkIos
107. ❝"A Kotlin Framework is like a Swift Framework"❞
108. ❝"A Kotlin Framework is like a Swift Framework"❞
109. ❝"A Framework is a Framework"❞
111. IDE
115. Digging Deeper
116. Testing
117. Testing ☞ Unit tests supported in Kotlin Multiplatform ☞ IDE support
118. import kotlin.test.* class TestFoo { @Test fun testBar() { assertTrue { Foo().bar().startsWith("bar-") } } } ... Kotlin/Native requires additional configuration → please refer to our blogs
119. Digging Deeper Objective-C Headers
120. Objective-C Generated Headers
121. Objective-C Generated Headers └── KotlinSlideParser.framework ├── Headers │ └── KotlinSlideParser.h ‏‏‏ ├── Info.plist ├── KotlinSlideParser └── Modules └── module.modulemap
122. #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
123. 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 List<String> NSArray<NSString *> * [String] Int? Nullable NSNumber * NSNumber?
124. 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 -→
125. Digging Deeper Debugging
126. Debugging ☞ Debugging is supported ☞ Compiler produces a .dSYM file ☞ "official" LLVM symbolication file for debugging ☞ Allows using Xcode for debugging
127. Debugging (lldb) breakpoint set --func-regex "myFunc" (lldb) b kfun:
129. ❝Xcode is like AppCode!❞
130. Features ☞ Breakpoints ✅ ☞ Stack Trace ✅ ☞ Stepping ✅ ☞ Object Value Inspection ⚠
131. Digging Deeper Memory Management
132. Memory Management ☞ ARC-based... ☞ ...with an automatic cycle collector on top ☞ Garbage Collection is performed periodically ☞ weak references supported since 0.7
133. Digging Deeper Exceptions
134. Exceptions ☞ All exceptions are unchecked in Kotlin ☞ @Throws is not supported in Kotlin/Native ☞ Cannot bridge Kotlin Exceptions to Swift Errors
135. 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 ...
137. Digging Deeper Concurrency
138. Concurrency Kotlin/Native supports: ☞ Workers (specific to Kotlin/Native) ☞ Coroutines! ☞ kotlinx.coroutines available since September ☞ Only single-threaded code is currently supported
139. In Action!
140. 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>? { return this.pageParser().process(string) } }
141. 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 } }
142. 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 } }
145. So this thing is perfect! Right?
146. Current Limitations
147. Still a Technology Preview
148. Current Limitations ☞ Compilation time ☞ Binary size ☞ Not 100% compatible with iOS bitcode ☞ Some everyday functions not available in K/N ☞ Lacking documentation
149. Open Questions ☞ GC-like memory model: strength or weakness? ☞ How to overcome platform differences? ☞ e.g. Concurrency / Workers
150. The Future is Now
151. The Future is Now ☞ Feature parity between Kotlin dialects ☞ New common extensions: ☞ coroutines ✅ ☞ Limited IDE support ✅ ☞ Simplified MPP Support ✅ ☞ Cannot inspect objects in the debugger ✅ ☞ Direct Interoperability with Swift ☞ Some new announcements at KotlinConf?
152. Summing Up
153. Kotlin Multiplatform + Kotlin/Native
154. Technology Preview
155. Encourages Modularity
156. Feels Familiar to All Mobile Developers
157. A New Approach to Cross-Platform
162. Thank You!
163. Simone @viteinfinite
164. Full demo: github.com/xebia-france/kotlin-ios- framework
165. Other Resources ☞ Kotlin Blog ☞ Deep Dive into Kotlin/Native by Andrey Breslav ☞ blog.xebia.fr | viteinfinite.com ☞ github.com/JetBrains/kotlin-mpp-example ☞ Kotlin Slack