As a previous sleep away camp attendee and with two kids currently involved with sleep away camps, computers are typically avoided at traditional summer camps.
You may have to consider sending your son to two different camps during the summer - one that focuses on iPhone development and one for all of the other activities he would like to be involved in.
My son is a competitive gymnast. A traditional sleep away camp was not for him as he didn't like playing traditional sports. We now send him to International Gymnastics Camp for a few weeks and an elective-style sleep away called Island Lake (http://www.islandlake.com/) where he can focus on extreme sports.
I did find an iPhone development program at George Washington University for high schoolers (http://www.cs.gwu.edu/summercamp/index.html).
Maybe a two-week iPhone camp and 4-6 week traditional/elective camp?