Swift How to use single guard let statement for multiple UITextField

Question

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

    @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
    }

Answer 1

You could use an embedded function to generalize the validation and keep your guard statement focused on the valid scenario.

@IBAction func submitBankInfo(_ textField: UITextField) 
{
   self.view.endEditing(true)

   func validField(_ field:UITextField, _ message:String) -> String?
   { 
      if let fieldValue = field.text, fieldValue != ""
      { return fieldValue }
      OperationQueue.main.addOperation 
      { self.showAlert(title: "Error!", message: message) }
      return nil 
   }

   guard let accountOwner  = validField(accountOwnerTxt, "Account owner is required.Please enter your identification"),
         let accountNumber = validField(accountNumberTxt,"Account is required.Please enter your number"),
         let bvn           = validField(bvnTxt,          "BVN is required.Please enter your bank verification number(BVN)"),
         let bankName      = validField(nameOfBankTxt,   "Bank name required.Please enter your bank name")
   else  { return }

   // proceed with valid data ...
}