An enum provides a set of related values:

enum Direction {
    case up
    case down
    case left
    case right
}

enum Direction { case up, down, left, right }

Enum values can be used by their fully-qualified name, but you can omit the type name when it can be inferred:

let dir = Direction.up
let dir: Direction = Direction.up
let dir: Direction = .up

// func move(dir: Direction)...
move(Direction.up)
move(.up)

obj.dir = Direction.up
obj.dir = .up

The most fundamental way of comparing/extracting enum values is with a [switch](<http://stackoverflow.com/documentation/swift/207/switch#t=201604251548528035104>) statement:

switch dir {
case .up:
    // handle the up case
case .down:
    // handle the down case
case .left:
    // handle the left case
case .right:
    // handle the right case
}

Simple enums are automatically [Hashable](<https://developer.apple.com/library/ios/documentation/Swift/Reference/Swift_Hashable_Protocol/index.html#//apple_ref/swift/intf/s:Ps8Hashable>), [Equatable](<https://developer.apple.com/library/ios/documentation/Swift/Reference/Swift_Equatable_Protocol/index.html#//apple_ref/swift/intf/s:Ps9Equatable>) and have string conversions:

if dir == .down { ... }

let dirs: Set<Direction> = [.right, .left]

print(Direction.up)  // prints "up"
debugPrint(Direction.up)  // prints "Direction.up"