CoinExchange - CoinBase Applicant Programming Exercise

Notes:

0.

This project should build and run on an iOS Simulator without any changes.  To run on a device, you need to make changes to the Development Team and/or profiles.  I’ll leave figuring out the magic incantation to the tester.

1.

I believe that there was a pair of contradictory statements in the email describing this exercise:

"The GDAX API exposes an endpoint to retrieve the current order book for each currency pair. For this task, you should use the level 2 query parameter to fetch aggregated order information."


"The application should be a client-side application that does not depend on a server. All API requests, form processing, and result display should be done client side in the mobile app."

It wasn't quite clear to me whether I was to access GDAX over the network, or whether to "not depend on a server" and do everything client-side.

The latter meant that I would have to use a dummy orderbook table, which, I decided, would  take me longer to create by hand, and vary, than just go ahead and get from GDAX over the network.


2.

I have the app access the orderbooks once every 15 seconds.  During testing, I noticed that GDAX would sometimes return a "Rate limit exceeded".  I presume that this is not an issue with my code, and could be due to the 15 second queries.

3.  

There’s much I’d like to add, such as an indicator when an update occurs, or pausing/resuming auto-updates...