Callback when the keyboard(or input) is dismissed?

[hao]

I am using IBAForms, there is a screen with several fields, when of them is the BSB number of an account, and once this is entered, I use the BSB number to request the name of the bank, which is then filled in for another field. Currently I am listening to 

IBAInputRequestorFormFieldDeactivated and if the field deactivated is that BSB field, I make the request, but when user taps Prev/Next button, it is also considered as 'deactivated', but what I exactly want is that I only make the request when the keyboard(or any other input) is dismissed, so I do not make request when user goes through the fields by tapping prev/next. So the question is, what is the callback for that and where can I access it?

Thanks a lot!