Comment Redpark serial cable for iOS (Score 1) 273
If you're developing for iOS, consider the Redpark serial cable: http://www.redpark.com/c2db9.html I have one and have personally made an LED blink from my very own custom-written iOS app. From what I'm told, this is the only general use serial cable which has ever made it through Apple's hardware approval process (which is prohibitively expensive for any "person" who isn't also a corporation). Alastair Allen gave a great workshop at OSCON in 2012 demonstrating to use of this serial cable with custom iOS apps: http://www.oscon.com/oscon2012/public/schedule/detail/24068
Additionally, with the adoption of Bluetooth 4 in iOS devices, that is also another way to connect hardware to custom mobile phone software without having use the Apple hardware partner program.