Cryptowatcher

An API client for Cryptowatch written in swift.

Cryptowatcher uses the Codable protocol introduced in Swift 4 to decode JSON data from the Cryptowatch API. All network calls are made wtih URLSession and provide a promise-based interface through then.

Compatibility

This project requires Swift 4/Xcode 9.

Example

Each of the get functions for Cryptowatcher will return a Promise for a corresponding struct representing the response. In the example below, getMarketPrice returns Promise<GetMarketPrice>.

Cryptowatcher().getMarketPrice(exchange: "gdax", pair: "btcusd").then { response in
  let price = response.result.price
  let remainingAllowance = response.allowance.remaining
  // Use the values to do something fun
}.onError { error in
  // Handle the error
}

Carthage

This project currently uses Carthage to manage it's dependency on then.

Testing

Decoding is fully tested through fixtures generated using a simple script located at bin/load_fixtures.sh. These fixtures are committed but may be refreshed to test against newer data.

To generate new fixtures:

1. Make the script executable (only once): chmod u+x ./bin/load_fixtures.sh
2. Run the script ./bin/load_fixtures.sh

Documentation

Code is fully documented and provides helpful hints such as an example URL, notes about API constraints and expected data formats. Documentation for the Cryptowatch API can be found at https://cryptowat.ch/docs/api.

Future

This is a very early version providing basic fetch functionality. The following are considerations for future versions:

• Pick a mocking approach and implement tests for all of the network calls.
• Remove then in favor of a baked-in promise solution or adopt a less attractive interface.
• Facilitate polling with respect paid to the CPU allowance.
• Add CocoaPods support