[Swift 공식 문서] 5. Control Flow

let names = ["Anna", "Alex", "Brian", "Jack"] for name in names { print("Hello, \(name)!") } // Hello, Anna! // Hello, Alex! // Hello, Brian! // Hello, Jack!

let numberOfLegs = ["spider": 8, "ant": 6, "cat": 4] for (animalName, legCount) in numberOfLegs { print("\(animalName)s have \(legCount) legs") } // cats have 4 legs // ants have 6 legs // spiders have 8 legs

for index in 1...5 { print("\(index) times 5 is \(index * 5)") } // 1 times 5 is 5 // 2 times 5 is 10 // 3 times 5 is 15 // 4 times 5 is 20 // 5 times 5 is 25

let base = 3 let power = 10 var answer = 1 for _ in 1...power { answer *= base } print("\(base) to the power of \(power) is \(answer)") // Prints "3 to the power of 10 is 59049"

let minutes = 60 for tickMark in 0..<minutes { // render the tick mark each minute (60 times) }

let minuteInterval = 5 for tickMark in stride(from: 0, to: minutes, by: minuteInterval) { // render the tick mark every 5 minutes (0, 5, 10, 15 ... 45, 50, 55) }

let hours = 12 let hourInterval = 3 for tickMark in stride(from: 3, through: hours, by: hourInterval) { // render the tick mark every 3 hours (3, 6, 9, 12) }

while condition { statements }

repeat { statements } while condition

var temperatureInFahrenheit = 30 if temperatureInFahrenheit <= 32 { // 조건이 참이면 print("It's very cold. Consider wearing a scarf.") //출력 } // Prints "It's very cold. Consider wearing a scarf."

temperatureInFahrenheit = 40 if temperatureInFahrenheit <= 32 { print("It's very cold. Consider wearing a scarf.") } else { print("It's not that cold. Wear a t-shirt.") } // Prints "It's not that cold. Wear a t-shirt."

temperatureInFahrenheit = 90 if temperatureInFahrenheit <= 32 { print("It's very cold. Consider wearing a scarf.") } else if temperatureInFahrenheit >= 86 { print("It's really warm. Don't forget to wear sunscreen.") } else { print("It's not that cold. Wear a t-shirt.") } // Prints "It's really warm. Don't forget to wear sunscreen."

temperatureInFahrenheit = 72 if temperatureInFahrenheit <= 32 { print("It's very cold. Consider wearing a scarf.") } else if temperatureInFahrenheit >= 86 { print("It's really warm. Don't forget to wear sunscreen.") }

switch some valueToConsider { case value1: //valueToConsider 이 value1 값과 같을 때 실행되는 블럭 case value2, value3: //valueToConsider 이 value1 값과 같을 때 실행되는 블럭 default: //valueToConsider 이 value1 값과 같을 때 실행되는 블럭 }

let someCharacter: Character = "z" switch someCharacter { case "a": print("The first letter of the alphabet") case "z": print("The last letter of the alphabet") default: print("Some other character") } // Prints "The last letter of the alphabet"

let anotherCharacter: Character = "a" switch anotherCharacter { case "a": // Invalid, the case has an empty body case "A": print("The letter A") default: print("Not the letter A") } // This will report a compile-time error.

let anotherCharacter: Character = "a" switch anotherCharacter { case "a", "A": // 여러개의 케이스를 묶을 수 있음 print("The letter A") default: print("Not the letter A") } // Prints "The letter A"

let approximateCount = 62 let countedThings = "moons orbiting Saturn" let naturalCount: String switch approximateCount { case 0: naturalCount = "no" case 1..<5: naturalCount = "a few" case 5..<12: naturalCount = "several" case 12..<100: naturalCount = "dozens of" case 100..<1000: naturalCount = "hundreds of" default: naturalCount = "many" } print("There are \(naturalCount) \(countedThings).") // Prints "There are dozens of moons orbiting Saturn."

let somePoint = (1, 1) switch somePoint { case (0, 0): print("\(somePoint) is at the origin") case (_, 0): print("\(somePoint) is on the x-axis") case (0, _): print("\(somePoint) is on the y-axis") case (-2...2, -2...2): print("\(somePoint) is inside the box") default: print("\(somePoint) is outside of the box") }

let anotherPoint = (2, 0) switch anotherPoint { case (let x, 0): print("on the x-axis with an x value of \(x)") case (0, let y): print("on the y-axis with a y value of \(y)") case let (x, y): print("somewhere else at (\(x), \(y))") } // Prints "on the x-axis with an x value of 2"

let yetAnotherPoint = (1, -1) switch yetAnotherPoint { case let (x, y) where x == y: print("(\(x), \(y)) is on the line x == y") case let (x, y) where x == -y: print("(\(x), \(y)) is on the line x == -y") case let (x, y): print("(\(x), \(y)) is just some arbitrary point") } // Prints "(1, -1) is on the line x == -y"

let someCharacter: Character = "e" switch someCharacter { case "a", "e", "i", "o", "u": print("\(someCharacter) is a vowel") case "b", "c", "d", "f", "g", "h", "j", "k", "l", "m", "n", "p", "q", "r", "s", "t", "v", "w", "x", "y", "z": print("\(someCharacter) is a consonant") default: print("\(someCharacter) isn't a vowel or a consonant") } // Prints "e is a vowel"

let stillAnotherPoint = (9, 0) switch stillAnotherPoint { case (let distance, 0), (0, let distance): print("On an axis, \(distance) from the origin") default: print("Not on an axis") } // Prints "On an axis, 9 from the origin"

let puzzleInput = "great minds think alike" var puzzleOutput = "" let charactersToRemove: [Character] = ["a", "e", "i", "o", "u", " "] for character in puzzleInput { if charactersToRemove.contains(character) { continue // 다음 순회로 넘어감 } puzzleOutput.append(character) } print(puzzleOutput) // Prints "grtmndsthnklk"

let numberSymbol: Character = "三" // Chinese symbol for the number 3 var possibleIntegerValue: Int? switch numberSymbol { case "1", "١", "一", "๑": possibleIntegerValue = 1 case "2", "٢", "二", "๒": possibleIntegerValue = 2 case "3", "٣", "三", "๓": possibleIntegerValue = 3 case "4", "٤", "四", "๔": possibleIntegerValue = 4 default: break // 다른 경우의 수에 대해서는 어떠한 코드도 실행하고 싶지 않을 때, } if let integerValue = possibleIntegerValue { print("The integer value of \(numberSymbol) is \(integerValue).") } else { print("An integer value couldn't be found for \(numberSymbol).") } // Prints "The integer value of 三 is 3."

let integerToDescribe = 5 var description = "The number \(integerToDescribe) is" switch integerToDescribe { case 2, 3, 5, 7, 11, 13, 17, 19: description += " a prime number, and also" fallthrough default: description += " an integer." // 이 코드도 실행됩니다. } print(description) // Prints "The number 5 is a prime number, and also an integer."

gameLoop: while square != finalSquare { diceRoll += 1 if diceRoll == 7 { diceRoll = 1 } switch square + diceRoll { case finalSquare: // diceRoll will move us to the final square, so the game is over break gameLoop // switch 문이 아닌 while 문을종료 case let newSquare where newSquare > finalSquare: // diceRoll will move us beyond the final square, so roll again continue gameLoop default: // this is a valid move, so find out its effect square += diceRoll square += board[square] } } print("Game over!")

func greet(person: [String: String]) { guard let name = person["name"] else { return // name 의 key 값이 존재하지 않는다면 함수 실행 종료 } print("Hello \(name)!") // 이를 사용해야하기 떄문입니다. guard let location = person["location"] else { print("I hope the weather is nice near you.") return } print("I hope the weather is nice in \(location).") } greet(person: ["name": "John"]) // Prints "Hello John!" // Prints "I hope the weather is nice near you." greet(person: ["name": "Jane", "location": "Cupertino"]) // Prints "Hello Jane!" // Prints "I hope the weather is nice in Cupertino."

if #available(iOS 10, macOS 10.12, *) { // Use iOS 10 APIs on iOS, and use macOS 10.12 APIs on macOS } else { // Fall back to earlier iOS and macOS APIs }