title: Binary operator '+' cannot be applied to operands of type 'String' and 'String exclamationmark
body: <p>I am generating a QRCode with name, email and phone number of user which are entered in registration form. In RegistrationVC, I have used userdefaults to save all these 3 fields.  Now in my QRGenerate VC, with the help of user default I want to generate QR code, but throwing an error </p>
  
  <blockquote>
    <p>Binary operator '+' cannot be applied to operands of type 'String' and 'String!". </p>
  </blockquote>
  
  <p>I am passing all three keys to a string (i.e.qrgeneratestring) and generating QRCodes.</p>
  
  <pre><code>phoneKeyValue = UserDefaults.standard.string(forKey: "phoneKey")
  nameKeyValue = UserDefaults.standard.string(forKey: "nameKey")
  emailidKeyValue = UserDefaults.standard.string(forKey: "emailIDKey")
  var qrgeneratestring = nameKeyValue + emailidKeyValue + phoneKeyValue
  
  
      if qrgeneratestring.isEmpty == false{
          let ciImageFromQRCode = generateQRCodeFromString(strQR: qrgeneratestring)
          let scaleX = (imgViewQRCode.frame.size.width / ciImageFromQRCode.extent.size.width)
          let scaleY = (imgViewQRCode.frame.size.height / ciImageFromQRCode.extent.size.height)
          let imgTransformed = ciImageFromQRCode.applying(CGAffineTransform(scaleX: scaleX, y: scaleY))
          imgViewQRCode.image = UIImage(ciImage: imgTransformed)
  
      }
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/362YQ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/362YQ.png" alt="enter image description here"></a></p>