IOS: Learning notes, Swift namespaces

In Swift, namespaces are implemented using Class (extension) nesting, which is shown in a simple example.

  main.swift//  swiftnamespace////  Created by Yao_yu on 14-8-1.//  Copyright (c) 2014 Yao_yu. All rights reserved.////  Swift namespaces use instance//import foundation//define top-level namespace class yy{}//define second-level namespaces in YY namespaces testextension The yy{class    test{    }}//defines the point class extension YY in the two-layer namespace. test{    class point2d{        var x:double = 0        var y:double = 0                Init (_ x:double, _ y:double) {            self.x = X
  self.y = y        }    }}func Main () {    //Use point    var pt = YY. TEST.POINT2D (123, 333)    println ("point coordinates are (\ (pt.x), \ (PT.Y))")        //results are point coordinates (123.0,333.0)}main ()