Applications that require data from real time events (such as a chat application, car location updates when you order an Uber and in the case of BUX the stock market prices) impose their own challenges. How to receive data updates? How to store data? Can you cache data at all? How to make sure data that is constantly changing is consistent throughout the app? iOS engineer Ian Guedes Maia of BUX shares the technologies they use to make their app perform well and reactive real-time to the ever changing stock market. Presented at the CocoaHeadsNL meetup on September 27th, 2017 at the BUX Office in Amsterdam.