Memo.swift

// Singleton
final class Singleton {
    static let shared = Singleton()
    private init() { // forbid object creation
    }
}


// Lazy
lazy var players = {
    return ["A", "B"]
}()
// -OR-
lazy var players = self.initialPlayers()
func initialPlayers() -> [String] {
    return ["A", "B"]
}


// Enumeration
let indexAndNum = [7, 8, 9, 10].enumerate().map { (index, element) in
    return "\(index): \(element)"
}


// Debug literals
print(#file #line #column #function)