Swift Basics

SWIFT BASICS
동의과학대학교 컴퓨터정보계열
김 종 현
jhkim@dit.ac.kr
www.facebook.com/jhkim3217
2014. 7. 19

Reference
• Swift Guide, 2014 AppCode.com
• Swift Tutorial: A Quick Start, Ray
Wenderlich
!

background
• new programming language for iOS, OS X
Apps
• Ruby, Python, Go… v.s. Objective-C
• Fast, Modern, Safe, Interactive
• Shorter, Cleaner, Easier to read
• 문법이 웹 개발자에게 친근(특히 Javascript 경험자)
• user friendly to new programmers

Variable, Constants,
Type Inference
• var : 변수
• let : 상수
!
var numberOfRow = 30
let maxNumberOfRows = 100
var  = “Have fun!” // emoji character
!
const int count = 10; // 항상 명시적으로 형 지정
double price = 23.55;
NSString *myMessage = @“Obj-C is not dead yet!”;
!

let count = 10
// count is inferred to be type Int
!
var price = 23.55
// price is inferred to be type Double
!
var myMessage = “Swift is the future”
// myMessage is inferred to be type String
!
var myMessage : String = “Swift is the future”

No Semicolons
var myMessage = “No semicolon is needed”
!
!

Basic String Manipulation
• String type is fully Unicode-compliant
!
// immutable String
let dontModifyMe = “You can’t modify this string”
!
// mutable String
var modifyMe = “You can modify this string”
!!
• String manipulation
!
let firstMessage = “Swift is awesome.”
let secondMessage = “What do you think?”
var message = firstMessage + secondMessage

// Objective-C
NSString *firstMessage = @“Swift is awesome.”;
NSString *secondMessage = @“What do you think?”
NSString *message = [NSString
stringWithFormat:@“%@%@“, firstMessage,
secondMessage];
NSLog(@“%@“, message);
!
!
!

• String Comparison
!
var string1 = “Hello”
var string2 = “Hello”
if string1 == string2 {
println(“Both are the same”)
} else {
println(”Both are different”)
}
!
결과 값은?
!
// Obj-C isEqualToString: method
!

Array
!
// Objective-C, store any type of objects
NSArray *recipes = @[@“짜장면”, @“짬뽕”, @“탕수육”,
@“군만두”, @“라면”];
!
// Swift, store items of the same type
var recipes = ["짜장면", "짬뽕", "탕수육", "군만두",
"라면", “우동”]
!
var recipes : String[] = ["짜장면", "짬뽕", “탕수육”,
"군만두", "라면"]
!
// recipes.count will return 5
var numberOfItems = recipes.count
!

// add items
recipes += “깐풍기”
!
// add multiple items
recipes += [“깐풍기”, “라조기”, “김밥 “]
!
// access or change a item in an array
var recipeItem = recipes[0]
recipes[1] = “떡뽁기”
!
// change a range of values
recipes[1…3] = [“우동”, “오향장육”, “팔보채”]
!
println(recipes)
!
!

Dictionary
// Objective-C
NSDictionary *companies = @{@“APPL” : @”Apple”,
@“GOOG” : @“Google”,
@“FB” : @“Facebook”};
!
// Swift
var companies = [“APPL” : “Apple”,
“GOOG” : “Google”,
“FB” : “Facebook”];
!
var companies: Dictionary<String, String> =
[“APPL” : “Apple”,
“GOOG” : “Google”,
“FB” : “Facebook”];
!

// Iteration
for (stockCode, name) in companies {
println(“(stockCode) = (name)”
}
!
for stockCode in companies.keys {
println(“Stock code = (stockCode)”)
}
!
for name in companies.values {
println(“Companies name = (name)”)
}
!
// add a new key-value pair to Dictionary
companies[“TWTR”] = “Twitter”

Classes
// define a class
class Recipe {
var name: String = “”
var duration: Int = 10
var ingredients: String[] = [“egg”]
}
!
// optional : ?
class Recipe {
var name:String? // assign default value of nil
var duration: Int = 10
var ingredients: String[]?
!
// create a instance
var recipeItem = Recipe()

// access or change the property variable
recipeItem.name = “짜장면”
recipeItem.duration = 30
recipeItem.ingredients = [“olive oil”, “salt”,
“onion”]
!
!
!
!
!
!

Obj-C subclass, protocol
Integration
// Objective-C
@interface SimpleTableViewController : UIViewController
<UITableViewDelegate, UITableViewDataSource>
!
!
// Swift
class SimpleTableViewController : UIViewController,
UITableViewDelegate, UITableViewDataSource
!
!

Methods
• define methods in class, structure or enumeration
• func keyword
!
class TodoManager {
func printWlecomeMessage() {
println(“Welcome to My ToDo List”)
}
}
!
// Swift method call
toDoManager.printWelcomeMessage()
!
// Objective-C
[toDoManager printWelcomeMessage];

// method arguments, return value
class ToDoManager {
func printWelcomeMessage(name:String) -> Int {
println(“Welcome to (name)’s toDo List”)
!
return 10
}
}
!
var toDoManager = TodoManager()
let numberOfTodoItem = todoManager.printWelcomeMessage(“Superman)
println(numberOfTodoItem)
!
!
!

Control Flow
• for loops
!
// ..
for i in 0..5 {
println(“index = (i)”)
}
!
for var i=0; i<5; i++ {
printf(“index = (i)”)
}

// …
for i in 0…5 {
println(“index = (i)”)
}
!
for var i=0; i<=5; i++ {
printf(“index = (i)”)
}
!

• if-else
!
var bookPrice = 1000
if bookPrice >= 999 {
println(“Hey, the book is expensive”)
} else {
println(“Okey, I can buy it”)
}
!
!

• switch
!
// break 문이 없음
swicth recipeName {
case “짜장면”:
println(“나의 주식!”)
case “떡뽁기”:
println(“나의 간사!”)
case “김밥”:
println(“제일 좋아하는 것!”)
default:
println(“모두 좋아해!”)
}
!

// range matching(.., …)
var speed = 50
switch speed {
case 0:
println(“stop”)
case 0…40:
println(“slow”)
case 41…70:
println(“normal”)
case 71..101
println(“fast”)
default:
println(“not classified yet!”)
}

Tuples
• multiple values as a single compound value
• any value of any type in the tuple
!
!
// create tuple
let company = (“AAPL”, “Apple”, 93.5)
!
// decomposing
let (stockCode, companyName, stockPrice) =
company
println(“stock code = (stockCode)”)
println(“company name = (companyName)”)
println(“stock price = (stockPrice)”)
!

// dot notation
let product = (id:”AP234”,
name:”iPhone6”,
price:599)
!
println(“id = (product.id)”)
println(“name = (product.name)”)
println(“price = USD(product.price)”)
!
!
!
!
!
!

// return multiple values in a method
class Store {
func getProduct(number: Int)->(id: String, name:
String, price: Int)
{
var id = “IP435”, name = “iMac”, price = 1399
switch number
{
case 1:
id = “AP234”
name = “iPhone 6”
price = 599
case 2:
id = “PE645”
name = “iPad Air”
price = 499
default:
break
}
return(id, name, price)
}
}
!
//call a method
let store = Store()
let product = store.getProduct(2)
println(“id = (product.id)”)
println(“name = (product.name)”)
println(“price = USD(product.price)”)

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