title: NSPredicate for regex pattern matching crashes
body: <p>This code:</p>
  
  <pre><code> internal let emailRegex:String = "[A-Z0-9a-z._%+-]+[A-Za-z0-9.-]+\\.[A-Za-z]{2,5}"
  
   let emailText = NSPredicate(format: "SELF MATCHES \(emailRegex)")
  
   return emailText .evaluateWithObject(email)
  </code></pre>
  
  <p>Crashes with error:</p>
  
  <blockquote>
    <p>'NSInvalidArgumentException', reason: 'Unable to parse the format
    string "SELF MATCHES [A-Z0-9a-z._%+-]+[A-Za-z0-9.-]+.[A-Za-z]{2,5}"'</p>
  </blockquote>