codecanyon-29640947-RevER – Exchange Rate.zip

1. RevER – Exchange Rate

It uses a VIP pattern for separation of concerns
It uses most of the common iOS design patterns, such as the delegate and observer
It uses proper Autolayout in the xibs
It uses UserDefaults to save the apps state
It uses localization for strings
Unit tests included

1. Choose a currency pair
   Initially the user is presented with an empty table and can use it to add a currency pair.
   Available currencies are loaded from a json file, with an image and currency description.

1. Currency chooser
   If so, a currency chooser table is presented and the user can choose the first currency
   and then the second currency.
   At any time, these currency chooser can be dismissed without altering the state of the app, either
   by using the close button, or the swipe down functionality if IOS14.
   These choosers properly disable selection of invalid currencies.

1. Fetch the exchange rate
   Upon choosing the second currency, we have a pair. This is automatically added to the initial currency table
   and a call is made to fetch its exchange rate.

1. Concurrent fetch and looper
   This API call is done every 1 sec (although this is not guaranteed by iOS itself).
   It fetches with a single call all the pairs.
   The loop timer is properly invalidated if we have no pairs.

1. Add more pairs
   The user is able to add another pair using the currency table header section. This functionality is the same as
   the one described above.

1. Delete a pair
   The user can delete a row, by long pressing on a cell for >1sec

1. Save state
   Currency pairs are saved on the phone, so next time the app starts, we resume the previous state.