Learn Kotlin from Swift perspective

Photo by Himesh Kumar Behera on Unsplash

I believe if we learn with comparison, we will learn faster so here I am, learning Kotlin from Swift perpective.

What is and what is not in the Swift ?

Why there is and why there is not in Swift ?

How I use them in Swift or Kotlin ?

If there is no equality can I build it my self ?

So this is the Comparison Table I have made, to make Kotlin more fun to learn.

Overloading

fun add(a: Int, b: Int): Int {
    return a + b
}

fun add(a: Double, b: Double): Double {
    return a + b
}

func add(a: Int, b: Int) -> Int {
    return a + b
}

func add(a: Double, b: Double) -> Double {
    return a + b
}s

Abstract

abstract class Animal(var name: String, var weight: Double, var age: Int, var isCarnivore: Boolean){
 
    fun eat(){
        println("$name sedang makan !")
    }
 
    fun sleep(){
        println("$name sedang tidur !")
    }
}

protocol Animal {
    var name: String { get set }
    var weight: Double { get set }
    var age: Int { get set }
    var isCarnivore: Bool { get set }
    
    func eat()
    func sleep()
}

extension Animal {
    func eat() {
        print("\(name) sedang makan !")
    }

    func sleep() {
        print("\(name) sedang tidur !")
    }
}

Extension Function

fun Int.square(): Int {
    return this * this
}

extension Int {
    func square() -> Int {
        return self * self
    }
}

Extension Variable

val String.length: Int
    get() = this.length

extension String {
    var length: Int {
        return self.count
    }
}

Visibility Modifier

public class PublicClass {}
internal class InternalClass {}
protected class ProtectedClass {}
private class PrivateClass {}

public class PublicClass {}
internal class InternalClass {}
fileprivate class FilePrivateClass {}
private class PrivateClass {}

Late init

lateinit var text: String

var text: String?

Lazy Initialization

val text: String by lazy {
    "Hello"
}

lazy var text: String = "Hello"

Primary Constructor

class Person(val name: String)

struct Person {
    var name: String
}

// OR

struct Person {
    var name: String
    init(name: String) {
        self.name = name
    }
}

Secondary Constructor

class Person {
    var name: String

    constructor(name: String) {
        this.name = name
    }

    constructor() {
        this.name = "John Doe"
    }
}

class Person {
    var name: String
    init(name: String) {
        self.name = name
    }
    convenience init() {
        self.init(name: "John Doe")
    }
}

Default Constructor

class Person(val name: String = "John Doe")

struct Person {
    var name: String = "John Doe"
}

// OR

struct Person {
    var name: String
    init(name: String = "John Doe") {
        self.name = name
    }
}

Property Delegation

import kotlin.reflect.KProperty
 
class DelegateName {
    private var value: String = "Default"
 
    operator fun getValue(classRef: Any?, property: KProperty<*>) : String {
        println("Fungsi ini sama seperti getter untuk properti ${property.name} pada class $classRef")
        return value
    }
 
    operator fun setValue(classRef: Any?, property: KProperty<*>, newValue: String){
        println("Fungsi ini sama seperti setter untuk properti ${property.name} pada class $classRef")
        println("Nilai ${property.name} dari: $value akan berubah menjadi $newValue")
        value = newValue
    }
}

class Animal {
    var name: String by DelegateName()
}

@propertyWrapper
struct DelegateName {
    private var value: String

    var wrappedValue: String {
        get {
            print("Fungsi ini sama seperti getter untuk properti \(propertyName)")
            return value
        }
        set {
            print("Fungsi ini sama seperti setter untuk properti \(propertyName)")
            print("Nilai \(propertyName) dari: \(value) akan berubah menjadi \(newValue)")
            value = newValue
        }
    }

    private var propertyName: String = "Default"

    init(wrappedValue: String) {
        self.value = wrappedValue
    }

    init() {
        self.value = "Default"
    }
}

class Animal {
    @DelegateName var name: String
}

Next is Special Class and Collection