[SwiftPH + PADC Meetup - May 2019] Swift Kotlin Syntax Comparison by Mark Kevin King About the speaker: Mark Kevin King (https://twitter.com/swiftymarks) is a guy who now works for himself and have partnerships with different companies. Born as an iOS developer but also does Android Development and Rails API. Workaholic? Yes! Trying hard to be a Sage developer. He has been developing mobile apps for more than 4 years now. One proud work to be released soon in the market is the Krispy Kreme App. Yum! About SwiftPH: SwiftPH and iOSCodersPH are the Apple Developer Communities in the Philippines. SwiftPH is responsible for our meetups and the iOSCodersPH is our slack group. Our community aims to bring all the iOS (and Apple) developer in the Philippines together to learn from one another and help our Apple developer ecosystem grow. If you are interested, join us at https://meetup.com/swiftph. You can also reach out to us at swiftphofficial@gmail.com. About Philippine Android Developer Community (PADC): Philippine Android Developer Community is the Android developer community in the Philippines. (https://www.meetup.com/Philippine-Android-Developers-Community) About the event: Date: May 18, 2019 Venue: BeautyMNL, Philippines More info here: https://www.meetup.com/SwiftPH/events/261166657/

1. Swift + Kotlin
Comparison

2. Outline
• History
• Basics
• Playgrounds vs. Main function
• Declaring functions
• Single-expression function
• Variable declarations
• Nullable
• String interpolations

3. Swift Language (History)
• Introduced in 2014
• Upgraded to v1.2 in 2014
• Swift 2
• Swift 2.2 (Open Source)
• Swift 3 - 2016
• Swift 4 - 2017
• Swift 5 - Now

4. Kotlin Language (History)
• Introduced by Jetbrains 2011
• Kotlin v1.0 - Feb 2016
• 2017 - First class support for Kotlin in Android
• Kotlin v1.2 - Sharing code between JVM and Javascript
platforms
• Kotlin v1.3 - October 2018
• Google I/0 2019 - Preferred language for Android App
Developers

5. Swift Interactive
• Playgrounds

6. Kotlin Interactive
• Main Function
• Kotlin Interactive Shell

7. Variable Declaration
Kotlin
var number = 42
Swift
var number = 42

8. Variable Declaration
(Constant)
Kotlin
val number = 42
Swift
let number = 42

9. Variable Declaration
(Global Constant)
Kotlin
const val number = 42
Swift
let number = 42

10. Declaring Functions
Kotlin
fun functionName(param1: Type1, param2: Type2, paramN: TypeN): ReturnType {
// Function contents goes here……
}
Swift
func functionName(param1: Type1, param2: Type2, paramN: TypeN) -> ReturnType {
// Function contents goes here……
}

11. Nullable (New Concept)
Kotlin
var b: String? = “abc”
b = null //ok
print(b)
Swift
var b: String? = “abc”
b = nil //ok
print(b)

12. String interpolation
Kotlin
var b: String = “abc”
print(“Letter $b”) // Letter abc
Swift
var b: String = “abc”
print(“Letter (b)”) // Letter abc

13. Outline
• Control Structures
• If else
• Iterations
• Switch Statement

14. If Else (Single If)
Kotlin
// Traditional Usage
var max = a
if (a < b) max = b
Swift
// Traditional Usage
var max = a
if a < b {
max = b
}

15. If Else (Single If else)
Kotlin
var max: Int
if (a > b) {
max = b
} else {
max = b
}
Swift
var max = a
if a < b {
max = b
} else {
max = b
}

16. If Else
Kotlin
var max: Int
if (a > b) {
max = b
} else {
max = b
}
Swift
var max = a
if a < b {
max = b
} else {
max = b
}

17. If Else
Kotlin
var max: Int
if (a > b) {
max = b
} else {
max = b
}
Swift
var max = a
if a < b {
max = b
} else {
max = b
}

18. Fast Iterations
Kotlin
val names = arrayOf(“Mike”, “Matt”, “Kurt”, “Steffi”)
for (name in names) {
print(“Hello $name”)
}
Swift
let names = [“Mike”, “Matt”, “Kurt”, “Steffi”]
for name in names {
print(“Hello (name”))
}

19. For Loops
Kotlin
for (i in 1..3) {
println(i)
}
Swift
for i in 1…10 {
print(i)
}
Swift
for i in 1..<10 {
print(i)
}

20. While Loops
Kotlin
while (condition) {
statements
}
Swift
while condition {
statements
}
Swift
while x < 10 {
x = x + 1
}
Kotlin
while (x < 10) {
x = x + 1
}

21. Do While Loops
Swift
do {
} while condition
Kotlin
do {
} while (condition)

22. Switch Statement
Swift
switch value {
case value1:
//statement
case value2:
//statement
default:
break
}
Kotlin
when (value) {
value1 -> //statement
value2 -> //statement
else -> {
//statement
}
}

23. Outline
• Collections
• Hashes

24. Collections
Kotlin
val thresholds = intArrayOf(10, 20, 30, 40, 50)
Swift
let integers = [1, 2, 3, 4]
let strings = [“one”, “two”, “three”, “four”]
let doubles = [1.0, 2.0, 3.0, 4.0]
let objects = [dog, cat, tiger]

25. Collections functions
Swift
collection.append(object)
collection.remove(at: Int)
collection[x] = newValue //can only be done if not constant
println("Average: ${thresholds.average()}")
println(Max: ${thresholds.max()}")
println("Sum: ${thresholds.sum()}")
println("Count: ${thresholds.count()}")
println("Size: ${thresholds.size}")
println("First: ${thresholds.first()}")
println("Last: ${thresholds.last()}")
println("Index: ${thresholds[0]} == ${thresholds.get(0)}")
println("Slice: ${thresholds.sliceArray(1..3)
.toHashSet()
.toString()}")
thresholds = thresholds.plus("2")

26. Hashes
Kotlin
var dictionary: HashMap<String, String> = hashMapOf(“JFK” to
“John Kennedy Interational Airport”)
print(dictionary[“JFK”]) // “John Kennedy International Airport”
Swift
var dictionary = [String: String]()
dictionary = [“JFK”: “John Kennedy International Airport”]
print(dictionary[“JFK”]) // “John Kennedy International Airport”

27. Outline
• Classes
• Constructor
• Inheritance
• Lazy variables
• Data Classes
• Singletons

28. Classes
• Classes
• Constructor
• Inheritance
• Lazy variables
• Singletons

29. Class
Kotlin
class Dog {
}
Swift
class Dog {
}

30. Constructor (Kotlin)
Kotlin (Primary)
Kotlin (Secondary)
class Dog (breed: String){
constructor(){
}
}
Kotlin
class Dog (breed: String){
}

31. Constructor (Swift)
class Dog {
let name: String
let kind: String
init(name: String, kind: String) {
self.name = name
self.kind = kind
}
}

32. Inheritance
Swift
class Dog: Pet {
let name: String
let kind: String
init(name: String, kind:
String) {
self.name = name
self.kind = kind
}
}
Kotlin
class Dog: Pet {
constructor(name:String){
super.name = name
}
}

33. Lazy Variables
Swift
class Person {
let firstName: String
let lastName: String
var fullName: String {
return “(firstName) + (lastName)”
}
init(firstName: String, lastName: String) {
self.firstName = firstName
self.lastName = lastName
}
}
class Person(_firstname: String,
_lastname:String) {
var firstName: String
var lastName: String
init{
firstName = _firstname
lastName = _lastname
}
val fullName: String by lazy{
"$firstName $lastName"

34. Singletons
Swift
class LocationManager {
static let shared = LocationManager()
init() {
//Optional do what ever needed
}
}
Kotlin
object LocationManager {
init {
//Do What ever needed
}
}

35. Extension Functions
Swift
extension Type {
// New functionalities
goes here
func doSomething() {
}
}
Kotlin
class Type {
}
func Type.doSomething() {
}

36. Outline
• Protocols or Interfaces
• Closures or Lambda

37. Protocols or Interfaces
Swift
protocol Animal {
var canFly: Bool {get}
func eat()
func makeSound()
}
Kotlin
interface Person {
var canFly: Boolean
fun eat()
fun makeSound()
}

38. Closures
Swift
func animate(completion: @escaping() -> Void)
object.animate { Void in
// Do something
}

39. Lambda
Kotlin
fun animate(completion: (): Void)
object.animate( {
//Do something
})