Swift - 혼자 공부하면 분명히 안할테니까 같이 공부하기

//
var name = "Suyeol Jeon"
//
let birthyear = 1995

//
name = " "
//
birthyear = 2000
! Cannot assign to value: 'birthyear' is a 'let' constant

var name: String = "Suyeol Jeon"
let birthyear: Int = 1995
var height: Float = 180.1

var name: String = "Suyeol Jeon"
let birthyear: Int = 1995
var height: Float = 180.1
"ABC" String
123 Int

[String] [String: String]
let languages = [
"Swift",
"Objective-C",
"Python",
]
var capitals = [
" ": " ",
" ": " ",
" ": " ",
]

for _ in 0..<10 {
print("Hello!")
}
• for i in 0..<10  
i
•

switch age {
case 8..<14:
student = " "
case 14..<17:
student = " "
case 17..<20:
student = " "
default:
student = " "
}

var name: String = " "
name = nil
! Nil cannot be assigned to type 'String'
String nil

var name: String? = " "
name = nil
? String

nil
var email: String?
print(email) // nil
email = "devxoul@gmail.com"
print(email) // Optional("dev...com")

String? String
let optional: String? = "Hello"
let required: String = optional
! Value of optional type 'String?' not unwrapped; did you
mean to use '!' or '?'?

String? String
   
String String?

let optionalName: String? = " "
if let name = optionalName {
print(name)
}

print(name)
}
" "

print(name)
}
let name: String = " "

print(name) //
}

let optionalName: String?
print(name)
}

let optionalName: String?
print(name)
}
nil

if let name = optionalName,
let age = optionalAge {
print(name, age)
}

if let age = optionalAge
where age >= 20 {
print(age)
}
where

if let arr = optionalArray {
print(arr.isEmpty)
} else {
print(false)
}

print(optionalArray?.isEmpty == true)

print(optionalName) // Optional(" ")
print(optionalName!) //

var email: String! = " "
print(email) //
nil

func hello(name: String, time: Int) -> String {
var string = ""
for _ in 0..<time {
string += "(name) !n"
}
return string
}

func hello(name: String, time: Int) -> String {
var string = ""
for _ in 0..<time {
string += "(name) !n"
}
return string
}
hello(" ", time: 3)

func hello(name: String, numberOfTimes time: Int) -> Void {
print(time)
}
hello(" ", numberOfTimes: 3)

func hello(withName name: String,
numberOfTimes time: Int) -> Void {
print(time)
}
hello(withName: " ", numberOfTimes: 3)

func hello(name: String, _ time: Int) -> Void {
print(time)
}
hello(" ", 3)

func hello(name: String, time: Int = 1) -> Void {
print(time)
}
hello(" ")

func sum(numbers: Int...) -> Int {
var sum = 0
for number in numbers {
sum += number
}
return sum
}
sum(1, 2)
sum(3, 4, 5)

func hello(name: String, time: Int) {
func message(name: String) {
return "(name) !"
}
for _ in 0..<time {
print message(name)
}
}

func helloGenerator(message: String) -> String -> String {
func hello(name: String) -> String {
return name + message
}
return hello
}
let hello = helloGenerator(" !")
hello(" ")

func helloGenerator(message: String) -> (String, String) -> String {
func hello(firstName: String, lastName: String) -> String {
return lastName + firstName + message
}
return hello
}
let hello = helloGenerator(" !")
hello(" ", " ")

return { (firstName: String, lastName: String) -> String in
}
}
func hello(firstName: String, lastName: String) -> String {
}
return hello
}

return { (firstName: String, lastName: String) -> String in
}
}

return { firstName , lastName in
}
}

return { firstName, lastName in
}
}

return {
return $1 + $0 + message
}
}

return { $1 + $0 + message }
}
return {
return $1 + $0 + message
}
}

let hello: (String, String) -> String = { $1 + $0 + " !" }
hello(" ", " ")

let hello: ((String, String) -> String)? = nil
hello?(" ", " ")

func manipulateNumber(number: Int,
usingBlock block: Int -> Int) -> Int {
return block(number)
}
manipulateNumber(10, usingBlock: { (number: Int) -> Int in
return number * 2
})

manipulateNumber(10, usingBlock: {
$0 * 2
})
manipulateNumber(10, usingBlock: { (number: Int) -> Int in
return number * 2
})
manipulateNumber(10) {
$0 * 2
}

let numbers = [1, 3, 2, 6, 7, 5, 8, 4]
let sortedNumbers = numbers.sort { $0 < $1 }
print(sortedNumbers) // [1, 2, 3, 4, 5, 6, 7, 8]
let evens = numbers.filter { $0 % 2 == 0 }
print(evens) // [2, 6, 8, 4]

let arr1 = [1, 3, 6, 2, 7, 9]
let arr2 = arr1.map { $0 * 2 }
// [2, 6, 12, 4, 14, 18]

let arr1 = [1, 3, 6, 2, 7, 9]
arr1.reduce(0, combine: { $0 + $1 }) // 28

let arr1 = [1, 3, 6, 2, 7, 9]
0 1+

let arr1 = [1, 3, 6, 2, 7, 9]
0 1+ = 1

let arr1 = [1, 3, 6, 2, 7, 9]
1 3
0 1+ = 1
+

let arr1 = [1, 3, 6, 2, 7, 9]
1 3
0 1+ = 1
+ = 4

let arr1 = [1, 3, 6, 2, 7, 9]
1 3
0 1+ = 1
+ = 4
4 6+

let arr1 = [1, 3, 6, 2, 7, 9]
1 3
0 1+ = 1
+ = 4
4 6+ = 10

let arr1 = [1, 3, 6, 2, 7, 9]
arr1.reduce(0, combine: +) // 28

class Dog {
var name: String?
var age: Int?
func simpleDescription() -> String {
return "" (self.name)"
}
}
struct Coffee {
var name: String?
var size: String?
return "☕ (self.name)"
}
}

class Dog {
var name: String?
var age: Int?
init() {
self.age = 0 //
}
}

class Dog {
var name: String //
var age: Int?
init() {
self.age = 0
}
} ! Return from initializer without initializing all stored properties

class Dog {
var name: String = " "
var age: Int?
init() {
self.age = 0
}
}

class Dog: Animal {
var name: String?
var age: Int
override init() {
self.age = 0 //
super.init() //
// `self`
print(self.simpleDescription())
}
return "" (self.name)"
}
}

struct Hex {
var decimal: Int?
}

struct Hex {
var hexString: String? {
get {
if let decimal = self.decimal {
return String(decimal, radix: 16)
} else {
return nil
}
}
set {
if let newValue = newValue {
self.decimal = Int(newValue, radix: 16)
} else {
self.decimal = nil
}
}
}
}

struct Hex {
var hexCode: String? {
if let hex = self.hexString {
return "0x" + hex
}
return nil
}
}

struct Hex {
var decimal: Int? {
willSet {
print("(self.decimal) (newValue) .")
}
didSet {
print("(oldValue) (self.decimal) .")
}
}
}

var coffeeInfo = (" ", 5100)
coffeeInfo // (String, Int)
coffeeInfo.0 //
coffeeInfo.1 // 5100
coffeeInfo.1 = 5100

var namedCoffeeInfo = (coffee: " ",
price: 5100)
namedCoffeeInfo.coffee //
namedCoffeeInfo.price // 5100
namedCoffeeInfo.price = 5100

let (coffee, price) = (" ", 5100)
coffee //
price // 5100
let (_, latteSize, lattePrice) = (" ",
"Venti", 5600)
latteSize // Venti
lattePrice // 5600

func coffeeInfoForName(name: String) -> (name: String, price: Int)? {
let coffeeInfoList: [(name: String, price: Int)] = [
(" ", 5100),
(" ", 5600),
]
for coffeeInfo in coffeeInfoList {
if coffeeInfo.name == name {
return coffeeInfo
}
}
return nil
}
coffeeInfoForName(" ")?.price // 5100
coffeeInfoForName(" ")?.price // nil

enum Month: Int {
case January = 1
case February
case March
case April
case May
case June
case July
case August
case September
case October
case November
case December
}

enum Month: Int {
case ...
switch self {
case .January:
return "1 "
case .February:
return "2 "
case ...
return "..."
case .December:
return "12 "
}
}
}

let december = Month.December
print(december.simpleDescription()) // 12
print(december.rawValue) // 12

let october = Month(rawValue: 10)
print(october) // Optional(Month.October)

enum IssueState: String {
case Open = "open"
case Closed = "closed"
}
let state = IssueState(rawValue: "open")
print(state) // Optional(IssueState.Open)

enum Spoon {
case Dirt
case Bronze
case Silver
case Gold
}

enum Spoon {
case Dirt
case Bronze
case Silver
case Gold
}
let spoon: Spoon = .Gold
func doSomething(spoon: Spoon) {
// ...
}
doSomething(.Silver)

enum Error {
case InvalidParameter(String, String)
case Timeout
}
let error = Error.InvalidParameter(
"email",
" ."
)

if case .InvalidParameter(let field, let message) = error {
print(field) // email
print(message) // .
}

switch error {
case .InvalidParameter(let field, let message):
print(field) // email
print(message) // .
default:
break
}

public enum Optional<Wrapped> {
case None
case Some(Wrapped)
}

let age: Int? = 20
switch age {
case .None: // `nil`
print(" .")
case .Some(let x) where x < 20:
print(" ")
case .Some(let x) where x < 65:
print(" ")
default:
print(" ")
}

/// .
protocol Sendable {
var from: String? { get }
var to: String { get }
func send()
}

struct Mail: Sendable {
var from: String?
var to: String
func send() {
print("Send a mail from (self.from) to (self.to)")
}
}

func sendAnything<T: Sendable>(sendable: T) {
sendable.send()
}

protocol Messagable {
var message: String? { get }
}
protocol Sendable: Messagable {
// ...
}

let anyNumber: Any = 10
let anyString: Any = "Hi"
let anyInstance: AnyObject = Dog()

extension String {
var length: Int {
return self.characters.count
}
func reverse() -> String {
return self.characters.reverse()
.map { String($0) }
.joinWithSeparator("")
}
}

protocol Sendable {
var from: String? { get }
var to: String { get }
func send()
}
extension Sendable {
func debug() {
print("(self.from) -> (self.to)")
}
}

Swift - 혼자 공부하면 분명히 안할테니까 같이 공부하기

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