Kotlin for swift developers

AndroidKotlin.md

Overview

• Android Studio
• Demo homer-stories-kotlin
• Kotlin Playground

KotlinLang vs Swift

Syntax (slight differences):

Swift	Kotlin	Notes
let	val	immutable
var	var	mutable
nil	null	undefined
func	fun	function
protocol	trait	abastract/virtual
init	constructor	initialization
->	:	return value
Any	AnyObject
!	!!	force unwrap
->	:	return value
print	println

similarities:

lang:

• Eplicit Types: var name:String = "matt"
• Type Coercion: val age = 2
• Typing: both strong and static
• String Interpolation: var message = "$matt scored a ${score} " + "today."
• Rang Operators (Inclusive): for i in 0..<count { vs for (i in 0..count - 1) {
• Etensions
• Map, Filter, Reduce:
• vargs
• Tuple support: fun myTupel = (2,3,5)
• Supports Optionals: val name:String? = null explicity unwrap: name!! optional unwrap name?
• Closer/lambda support
• Name parameters (arguments)
• Computed properties get{ "hello" } and get() = "hello"
• switch when () {

Arrays (similar-ish, Kotlin Array vs Kotlin ArrayList ):

• Kotlin (mutable fixed size): val numbers = Array<Int>(5){0}
• Kotlin (mutable array, variable size): var names = ArrayList<String>()
• Kotlin (immutable array): val days = arrayOf("Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun")

Dictionaries Maps (similar-ish, HashMap vs mapOf):

• Kotlin (variable capacity):var namesWithAges = HashMap<String, Int>()
• Kotlin (fixed capacity): var namesWithAges = HashMap<String, Int>(20) //
• similar assignment. Kotlin: namesWithAges["John Doe"] = 34
• Kotlin (immutable): val namesWithAges = mapOf("John Doe" to 34, "Jane Doe" to 29)

concept of mutability and immutability properties:

• mutable properties: var vs var
• immutable Properties: let vs val

differences:

swift supports (kotlin does not):

• guard
• typealias
• tuples ( kotlin onlys supports tuples as return types)

kotlin supports (swift does not):

• guard

• class specific importation class import

• @annotations

• data classes vs struct (value types)

• kotlin classes are final by default

• memory allocation ?

• functional closers? un-winding?

Things to investigate:

• kotlin has no semantic for passing data by value ( struct ) ? Im not 100% sure if this is true

iOS vs Android

• UIViewController vs Activity
• UIView vs View/Widget
• Storyboard/xib vs xml layout
• segue vs intent
• simulator vs emulator
• 2x,3x vs mdpi,hdpi,...
• gradle vs pods

Misc

• Kotlin supports targets: ( JVM, Objective-C, JavaScript)
• json vs gson vs jxson : faster?

Learning Resources

Kotlin Web Playground

https://kotlinlang.org/

https://web.stanford.edu/class/cs193a/videos.shtml

• Lecture 01: Course introduction and first app
• Lecture 02: Layout
• Lecture 03: Widgets; Lists
• Lecture 04: More Lists; Files and Storage
• Lecture 05: Multiple Activities and Intents

https://adorahack.com

• https://adorahack.com/zero-to-kotlin-hero-kotlin-extensions
• https://adorahack.com/zero-to-kotlin-hero-data-classes-and-sealed-classes
• https://adorahack.com/zero-to-kotlin-hero-data-classes-and-sealed-classes
• https://adorahack.com/say-goodbye-to-nulls
• https://adorahack.com/zero-to-kotlin-hero-classes-in-kotlin
• https://adorahack.com/zero-to-kotlin-hero-variables-and-data-types