for

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

switch

• Switch case 안에 콤마(,)로 구분해서 복수의 case 조건을 혼합(compound)해 사용
• 튜플을 조건으로 사용

  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")
  }
  // Prints "(1, 1) is inside the box"
  

• 값 바인딩 (Value Bindings)

  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"
  

• case 에 where 사용

  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"
  

• 혼합 케이스, 값-바인딩

  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"
  

• fallthrough. 다음 case를 진행

  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."
  }
  print(description)
  // Prints "The number 5 is a prime number, and also an integer."
  

  Label

  label 이름과 while 조건을 넣어 특정 구문을 실행하는 구문으로 사용
  label name: while condition {
  statements
  }
  

  guard

  특정 조건을 만족하지 않으면 이 후 코드를 실행하지 않도록 방어코드를 작성 ```swift func greet(person: [String: String]) { guard let name = person[“name”] else { return }

  print(“Hello (name)!”)

  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.”

### 버전 확인
```swift
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
}