title: Swift How to use single guard let statement for multiple UITextField
body: <p>Hello All I am currently having issues tryin to use one guard let for a couple of textfield instaed of multiple guard let for each textfield and an UIAlertController if any textfield is empty. This is the code I tried below. But the alert controller is not being called. Can someone please advise me what am doing wrong</p>
  
  <pre><code>    @IBAction func submitBankInfo(_ textField: UITextField) {
         self.view.endEditing(true)
         guard let accountOwner = accountOwnerTxt.text, accountOwner !   
           = "", let accountNumber = accountNumberTxt.text, accountNumber !
         = "", let bvn = bvnTxt.text, bvn != "", let bankName = 
        nameOfBankTxt.text, bankName != "" else {
          if textField.text == nil {
              switch textField {
              case accountNumberTxt:
                  OperationQueue.main.addOperation {
                      self.showAlert(title: "Error!", message: "Account is required.Please enter your number")
                  }
              case bvnTxt:
                  OperationQueue.main.addOperation {
                      self.showAlert(title: "Error!", message: "BVN is required.Please enter your bank verification number(BVN)")
                  }
              case nameOfBankTxt:
                  OperationQueue.main.addOperation {
                      self.showAlert(title: "Error!", message: "Bank name     required.Please enter your bank name")
                  }
              default:
                  break
              }
          }
  
          return
      }
  </code></pre>