Appendix: Quick Reference Tables

The NMI Payment Device SDK provides asynchronous callbacks to handle device updates, transaction flow, and error handling. Below is a categorized reference.

Callback	Purpose	Next Action
`onAvailablePinPads`	Returns available readers	Select device & connect
`onConnectAndConfigureFinished`	Ready to transact	Start transaction
`onTransactionUpdate`	EMV progress updates	Update UI
`onTransactionFinished`	Transaction complete	Confirm/Void
`onSignatureVerification`	Signature required	Call `continueSignatureVerification()`
`onDeferredAuthorization`	Offline fallback possible	Call `continueDeferredAuthorization()`
`onProcessReceiptFinished`	Receipt delivered	Log result