Today I am working on incorporating in-app purchases into the iOS version of Pic-a-POD. My plan is to have the basic app be free, but that will only allow access to the large pic from one of the available sources. An in-app purchase will unlock full access.
I was following all the steps detailed in Apple’s documentation, and the actual coding was not complex. But it wasn’t working. You have to send a product request to the App Store and every time, mine kept coming back as an invalid ID.
Eventually, I stumbled across a wonderful blog by Troy Brant dealing all the steps I needed to perform. I highly recommend this to anyone planning on implementing in-app purchases: http://troybrant.net/blog/2010/01/in-app-purchases-a-full-walkthrough/
Troy pointed out that I was missing a step, which was that I had to upload a binary to iTunes Connect before this would work. Following his instructions, I created a developer certificate and provisioning profile, uploaded the binary and then rejected the binary so that it would not be reviewed, since the app is still not finished.
I was then able to get back a valid product ID from the App Store. I haven’t tested purchasing yet, although I have set up my test user account so I can try this without actually spending any money.