title: How to get the Power of some Integer in Swift language?
body: <p>I'm learning swift recently, but I have a basic problem that can't find an answer</p>
  
  <p>I want to get something like </p>
  
  <pre><code>var a:Int = 3
  var b:Int = 3 
  println( pow(a,b) ) // 27
  </code></pre>
  
  <p>but the pow function can work with double number only, it doesn't work with integer, and I can't even cast the int to double by something like Double(a) or a.double()...</p>
  
  <p>Why it doesn't supply the power of integer? it will definitely return an integer without ambiguity !
  and Why I can't cast a integer to a double? it just change 3 to 3.0 (or 3.00000... whatever)</p>
  
  <p>if I got two integer and I want to do the power operation, how can I do it smoothly?</p>
  
  <p>Thanks!</p>