For my last semester of college, I took a class on iOS development. The last assignment of the class was a five week project of our own choosing. My idea was to build a better bus locator app for the local bus service, CATA. The CATA available on the app store leaves a lot to be desired. Most notably, I want to see multiple bus routes on the map simultaneously. This is very useful for anyone that uses the buses to get around campus since there are four bus routes that go around campus. When you’re running for the bus, every second counts so it’s quite advantageous to be able to see all four campus routes on the same map at once.
The first challenge was getting access to the API that provides the bus location info. CATA provides a web-based bus locator at http://realtime.catabus.com/InfoPoint/, but this is quite basic; nothing more than the bus location and the data from the server is all XML (yuck). Fortunately, there is a new web-based bus locator at http://22.214.171.124/InfoPoint/. Besides the fact that it’s just an IP address, this page provides more information including the direction of the bus, how many people are on board, even the name of the driver and the format of the data from the server is JSON (yay!). But how to get URLs to get data from the API? This is actually quite easy with the Live HTTP Headers Firefox addon. Just refresh the page and look for RESTful URLs. For this project these turned out to be:
- http://126.96.36.199/InfoPoint/rest/RouteDetails/Get/[route ID] for info about a specified route. This includes info about buses on the route, the coordinates of each stop on the route, and the filename of the KML file for the route.
- http://188.8.131.52/InfoPoint/rest/StopDepartures/Get/[stop ID] for upcoming departures from the specified stop. This includes the route IDs of buses as well as their scheduled and expected times of arrival and departure in UNIX time.
- http://184.108.40.206/InfoPoint/Resources/Traces/[KML filename]. The KML file is used for drawing the line of the route on a map. The filename is given in the route details JSON file.
- There was also a resource for downloading all the available routes, but since these rarely change, I chose to keep a static copy of these in a plist distributed with the app so that it does not need to download them each time the app is started (like the existing CATA app does).