dispatchOnce.swift

// Examples of dispatch_once replacements with global or static constants and variables. 
// In all three, the initialiser is called only once. 

// Static properties (useful for singletons).
class Object {
    static let sharedInstance = Object()
}

// Global constant.
let constant = Object()

// Global variable.
var variable: Object = {
    let variable = Object()
    variable.doSomething()
    return variable
}()