To handle the push notifications on my iPhone I am using the Prowl API and iPhone app, which receives data via Pushingbox's API.
Go to www.prowlapp.com and register for an account and create an API key. Make note of your API key because you will need it when you set up your Pushingbox scenario.
Go to www.pushingbox.com and register for an account. Create a new service and select "CustomURL", not Prowl. It sounds counterintuitive, but the built in Prowl service does not have the functionality that I wanted. Name the service whatever you want, use the root URL "https://api.prowlapp.com/publicapi/" and change the method to "GET".
Add a device/scenario (name it whatever you want), then add an action and pick the service that you just created. In the data field enter: add?apikey=YOUR-API-KEY&application=Smoker&event=$event$
YOUR-API-KEY is the API key from Prowl. You can change the "Smoker" to whatever you would like, it is just the identifier for Prowl so you can tell which service is sending you the message in the event that you have multiple Prowl services operating.
The scenario you just created in Pushingbox will have a DeviceID that's something like "v1114F22692BN12G", you'll want to copy that value and paste it into your code (char devid[] = "YOUR DEVID FROM PUSHINGBOX"; )
That's pretty much all there is to it. I'm far from an expert and I was able to get it work with less information than what I have provided here, so I hope anyone who hopes to undertake a similar project is able to use this information and be successful. Feel free to post here with any questions or suggestions!