title: Private setter "set()" in Swift
body: <p>this is point example introduced pint structure setter getter provided by <a href="https://developer.apple.com/library/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Properties.html" rel="noreferrer">apple</a> how can make only setter private</p>
  
  <pre><code>struct Point {
      var x = 0.0, y = 0.0
  }
  struct Size {
      var width = 0.0, height = 0.0
  }
  struct Rect {
      var origin = Point()
      var size = Size()
      var center: Point {
          get {
              let centerX = origin.x + (size.width / 2)
              let centerY = origin.y + (size.height / 2)
              return Point(x: centerX, y: centerY)
          }
          set(newCenter) {
              origin.x = newCenter.x - (size.width / 2)
              origin.y = newCenter.y - (size.height / 2)
          }
      }
  }
  </code></pre>