Today we'll continue our look at interesting Swift features. Let's begin.

Type Matching with ‘is’

Try as we might, sometimes still we end up with an AnyObject or Any reference in our Swift code. We can ask if it is a given type or subtype using Swift's powerful pattern matching:

protocol Vehicle { }
struct Spaceship : Vehicle { }

let thing: Any = Spaceship()

if thing is Vehicle { print("let's move") }
else { print("can't move") }

Parsimonious Declarations

Hat tip to Erica Sadun for passing along this one. We can use a sort of Tuple-ish syntax to create a bunch of related references inline:

var (top, left, width, height) = (0.0, 0.0, 100.0, 50.0)
spaceship.width = width

Inline Closures

This technique has a few different applications, but one good example is capturing a value from a switch statement inline:

enum Theme {
  case Day, Night, Dusk, Dawn

  func apply() {
    // ...

    let backgroundColor: UIColor = {
      switch self {
        case Day: return UIColor.whiteColor()
        case Night: return UIColor.darkGrayColor()
      }
    }()

    // ... set backgroundColor on all UI elements
  }
}