2.swift

var directionToHead = CompassPoint.west

// or
var directionToHead: CompassPoint = .west

3.swift

switch directionToHead {
  case .west:
    print("do something")
  case .north:
    print("do another thing")
  default:
    break
}

4.swift

// Enumeration of type Fruit.
enum Fruit: Int {
  case apple = 1000
  case banana = 500
  case grape = 2500
}

// declare variable.
let orderedFruit: Fruit = .apple 

switch orderedFruit {
  default:
    print("\(orderedFruit.rawValue)원 주세요!")
}

5.swift

enum Cloud {
  case cirrus
  case cumulus
  case altocumulus
  case cumulonimbus
}

enum WeatherCondition {
  case sunny(temperature: Float)
  case rainy(inchesPerHour: Float)
  case cloudy(cloudType: Cloud, windSpeed: Float)
}

6.swift

// declare variables.
var today = WeatherCondition.sunny(24)
var yesterday = WeatherCondition.cloudy(Cloud.cirrus, 10)

switch today {
  case .sunny(let temperature):
    print("today's temperature is \(temperature).")
  
  case .rainy(let inchesPerHour):
    print("\(inchesPerHour) inches of rainwater.")
  
  case .cloudy(let cloudType, let windSpeed):
    switch cloudType {
      case .cirrus:
        print("it's cloudy cirrus.")
      default:
        print("somethig blah..")
    }
    print("wind speed: \(windSpeed)")
}

7.swift

enum ArithmeticExpression {
    case number(Int)
    indirect case addition(ArithmeticExpression, ArithmeticExpression)
    indirect case multiplication(ArithmeticExpression, ArithmeticExpression)
}

8.swift

func evaluate(_ expression: ArithmeticExpression) -> Int {
    switch expression {
        case let .number(value):
            return value
        case let .addition(left, right):
            return evaluate(left) + evaluate(right)
        case let .multiplication(left, right):
            return evaluate(left) * evaluate(right)
    }
}

9.swift

public enum Result<Value> {
    case Success(Value)
    case Failure(NSData?, ErrorType)
}