Transaction Events — Android

sdk.setTransactionEventListener(object : TransactionEventListener {
    override fun onTransactionStarted() { showPrompt("Hold card near back of phone") }
    override fun onCardDetected()       { showSpinner("Processing...") }
    override fun onTransactionApproved(r: TransactionResult) { hideSpinner(); showApproval(r) }
    override fun onTransactionDeclined(r: TransactionResult) { hideSpinner(); showDecline(r.responseText) }
    override fun onTransactionCancelled() { hideSpinner() }
})