title: How to use get and set in Swift
body: <p>I have a block of simple code calculating the area &amp; perimeter of a rhombus.</p>
  
  <pre><code> var perimeterOfRhombus: Double {
          get {
              let twoSides1 = sideLength1 + sideLength1
              let twoSides2 = sideLength2 + sideLength2
              let finalPerimeter = twoSides1 + twoSides2
              return finalPerimeter
          } set {
        }
      }
  </code></pre>
  
  <p>What I am missing is the set section. </p>
  
  <p>I want it to show what sideLength1 and sideLength2 were in the beginning.</p>
  
  <p>I am not sure what newValue is used for, when it has no value.</p>
  
  <p>It does work without using set, but I see on Apple's <code>swift</code> language guide that set and get usually go together. </p>
  
  <p>If set is really not needed in this code, what is it normally used for anyways?</p>