Kotlin For Swift Developers - CocoaHeads NL, Amsterdam, March 2018

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KOTLIN FOR SWIFT DEVELOPERS COCOAHEADS NL | AMSTERDAM | MARCH 2018 @DESIGNATEDNERD | BAKKENBAECK.COM | JUSTHUM.COM

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✨ " ☕ $ ✨

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WHAT IS KOTLIN ?

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WHY SHOULD I CARE?

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A CONSTANT STRING

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SWIFT let greeting = "Hello World"

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SWIFT let greeting = "Hello World" KOTLIN val greeting = "Hello World"

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AN OPTIONAL INTEGER VARIABLE

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SWIFT var something: Int?

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SWIFT var something: Int? KOTLIN var something: Int?

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☠ NullPointerException ☠

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GENERICS AND FUNCTIONS AS PARAMETERS

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SWIFT func useFunction(on item: T, function: (T) -> U) -> U { return function(item) } func insertExclamationPoint(in string: String) -> String { return string .components(separatedBy: " ") .joined(separator: "! ") } let result = useFunction(on: "try Swift", function: insertExclamationPoint(in:)) // result: "try! Swift"

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KOTLIN fun T.useFunction(action: (T) -> U): U { return action(this) } fun insertExclamationPoint(in: String) : String { return in.split(" ").joinToString("! ") } val result = "try Kotlin".useFunction { insertExclamationPoint(it) } // result: "try! Kotlin"

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map filter reduce

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map filter reduce*

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SWIFT let numbers = [ 1, 2, 3 ] let reduced = numbers.reduce(0, +) // reduced: 6

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SWIFT let numbers = [ 1, 2, 3 ] let reduced = numbers.reduce(0, +) // ! // reduced: 6

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SWIFT let numbers = [ 1, 2, 3 ] let reduced = numbers.reduce(0) { $0 + $1 } // reduced: 6

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SWIFT let numbers = [ 1, 2, 3 ] let reduced = numbers.reduce(20) { $0 + $1 } // reduced: 26

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SWIFT let numbers = [ 1, 2, 3 ] let reduced = numbers.reduce(20) { $0 + $1 } // reduced: 26 KOTLIN val numbers = arrayOf(1, 2, 3) val reduced = numbers.reduce { total, current -> total + current } // reduced: 6

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SWIFT let numbers = [ 1, 2, 3 ] let reduced = numbers.reduce(20) { $0 + $1 } // reduced: 26 ⬆ KOTLIN val numbers = arrayOf(1, 2, 3) val reduced = numbers.reduce { total, current -> total + current } // reduced: 6

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SWIFT let numbers = [ 1, 2, 3 ] let reduced = numbers.reduce(20) { $0 + $1 } // reduced: 26 KOTLIN val numbers = arrayOf(1, 2, 3) val folded = numbers.fold(20) ⬅ { total, current -> total + current } // folded: 26

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SWIFT let doubled = [ 1, 2, 3 ].map { $0 * 2 }

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SWIFT let doubled = [ 1, 2, 3 ].map { $0 * 2 } KOTLIN arrayOf(1, 2, 3).map { it * 2 }

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SWIFT let doubled = [ 1, 2, 3 ].map { $0 * 2 } KOTLIN arrayOf(1, 2, 3).map { it * 2 }

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SWIFT let numbers = [ 1, 2, 3 ] let reduced = numbers.reduce(20) { $0 + $1 } // reduced: 26

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$0 $1 $2...$∞

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SWIFT let numbers = [ 1, 2, 3 ] let reduced = numbers.reduce(20) { $0 + $1 } // reduced: 26 KOTLIN val numbers = arrayOf(1, 2, 3) val folded = numbers.fold(20) { total, current -> total + current } // folded: 26 ⬆

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!"#

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guard

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NOW (KOTLIN) optionalThing?.let { it.doSomething() }

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NOW (WORSE KOTLIN) if (optionalThing != nil) { optionalThing!!.doSomething() }

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PROPOSED (KOTLIN) guard val thing = optionalThing else { return } thing.doSomething()

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apply

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NOW (SWIFT) UserDefaults.standard.set(true, forKey: "DefaultOne") UserDefaults.standard.set(false, forKey: "DefaultTwo)

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NOW (BETTER SWIFT) let defaults = UserDefaults.standard defaults.set(true, forKey: "DefaultOne") defaults.set(false, forKey: "DefaultTwo)

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PROPOSED (SWIFT) UserDefaults.standard.apply { "DefaultOne" = true, "DefaultTwo" = false, }

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KOTLIN / NATIVE

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LLVM

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LLVM

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LLVM

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SUPPORTED PLATFORMS ▸ x86-64 (macOS, Linux, Windows) ▸ arm64 (iOS, Android) ▸ arm32 (Android) ▸ arm32 hardfp (Raspberry Pi) ▸ WebAssembly (Web)

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DOCUMENTATION

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DOCUMENTATION? ¯\_(ϑ)_/¯

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KOTLIN: ☕ OR " = #

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try? kotlin

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https://try.kotlinlang.org

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EDU TOOLS PLUGIN FOR INTELLIJ OR ANDROID STUDIO

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OBLIGATORY SUMMARY SLIDE ▸

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OBLIGATORY SUMMARY SLIDE ▸ Make Friends With Android

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OBLIGATORY SUMMARY SLIDE ▸ Make Friends With Android ▸ Kotlin Native Is Cool But Not Ready For Production

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OBLIGATORY SUMMARY SLIDE ▸ Make Friends With Android ▸ Kotlin Native Is Cool But Not Ready For Production try! Kotlin

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ONE MORE THING

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ONE MORE THING: (A SHAMELESS PLUG!)

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BEDANKT, EN TOT ZIENS!

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LINKS! ▸ Kotlin Home & Documentation: https://kotlinlang.org ▸ KotlinConf iOS App in Kotlin/Native: https://github.com/JetBrains/kotlinconf- app/tree/master/ios ▸ The Edu Tools Plugin for IntelliJ or Android Studio https://kotlinlang.org/docs/tutorials/ edu-tools-learner.html

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MORE LINKS! ▸ Creating an iOS Framework With Kotlin http://viteinfinite.com/2018/02/creating- an-ios-framework-with-kotlin ▸ RayWenderlich.com Android Avalanche™ https://www.raywenderlich.com/187520/ introducing-the-android-avalanche

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ILLUSTRATION CREDITS ▸ Monica Komperda, Native Code Forever (Hire her! She's awesome!) http://mokomperda.com/design