setCustomerUserId method
Setting your own customer ID enables you to cross-reference your own unique ID with AppsFlyer’s unique ID and the other devices’ IDs. This ID is available in AppsFlyer CSV reports along with Postback APIs for cross-referencing with your internal IDs.
Implementation
void setCustomerUserId(String id) {
_methodChannel.invokeMethod("setCustomerUserId", {'id': id});
}