I built an 
app that can show you the 
journeys you’ve made using your 
, along with their associated charges 
:
https://itunes.apple.com/gb/app/oyster-tfl-contactless-card/id1116225263?ls=1&at=1001lnJf&mt=8
Journeys made using a (or any other contactless ) appear in the app not long after completing the journey. Journeys made using an Oyster card can take up to 24 hours to appear.
Once the API is ready it would be easy to show this info in the app, similar to what Flux are doing with receipts 