title: "initialize" class method for classes in Swift?
body: <p>I'm looking for behavior similar to Objective-C's <code>+(void)initialize</code> class method, in that the method is called once when the class is initialized, and never again thereafter.</p>
  
  <p>A simple <code>class init () {}</code> in a <code>class</code> closure would be really sleek! And obviously when we get to use "<code>class var</code>s" instead of "<code>static var</code>s in a struct closure", this will all match really well!</p>