What is the customIdentifier?
The Peach Payments SDKs for iOS and Android do allow you to provide your unique order ID or Transaction ID.
This is helpful in reconciling the transaction / payment with the orders in your databases / back-end.
Both the iOS and Android SDKs have the same parameter where you can provide your order ID / Transaction ID. This is:
customIdentifier - This will be your order ID or transaction ID. This is important for reconciliation later with your accounts / order system
Please see this link: http://www.peachpayments.mpymnt.com/node/29 and scroll down to "Other Payment Parameters" for more information