Example code -

@IBAction func beginScanning(_ sender: Any) {
    guard NFCNDEFReaderSession.readingAvailable else {
        let alertController = UIAlertController(
            title: "Scanning Not Supported",
            message: "This device doesn't support tag scanning.",
            preferredStyle: .alert
        )
        alertController.addAction(UIAlertAction(title: "OK", style: .default, handler: nil))
        self.present(alertController, animated: true, completion: nil)
        return
    }


    session = NFCNDEFReaderSession(delegate: self, queue: nil, invalidateAfterFirstRead: false)
    session?.alertMessage = "Hold your iPhone near the item to learn more about it."
    session?.begin()
}

• Go to this link for more details -

https://developer.apple.com/documentation/corenfc/building_an_nfc_tag-reader_app