Mike Colagrosso created Avviso, a Processing and Arduino library for sending push alerts to iOS devices using the Prowl API. This would make projects such as Snail Mail Push Alerts a much easier task because a PHP web server is not needed in the set up. The libraries, example code, and set up guide are available on Github.
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Don’t use Prowl. Use Notifo instead, it’s free and has a much better API. There’s even a beta Android app for it.