title: iOS Add multiple optional value in Swift3
body: <pre><code>var a: CGFloat!  
  var b: CGFloat!  
  var c: CGFloat!  
  </code></pre>
  
  <p>After init then </p>
  
  <pre><code>let x = a + b + c
  </code></pre>
  
  <p>The Xcode8 would show </p>
  
  <p><strong><em>Binary operator '+' cannot be applied to operands of type 'CGFloat' and 'CGFloat!'</em></strong></p>
  
  <p>guess first add two of them made this Error</p>
  
  <p>Maybe I could use first add one and then add third to fix</p>
  
  <p>But It will change my x to var and not concise as past </p>
  
  <p>Any Suggestion?</p>
  
  <hr>
  
  <p><em>Edit: there must some application scenarios we could faced, I wrote this simple demo just 4 express this issue :)</em></p>