To develop apps for the iPhone, iPad, or iPod touch, you'll need to register as an iOS developer. Although you can register for free, all that gets you is the development tools. You won't be able to deploy your apps to a real device. It's $99 a year for an individual developer, $299 for Enterprises (this option lets you deploy apps directly to your team), and free for educational institutions (which also lets you deploy apps to a team).
Before you go any further, please make sure you can create and run simple apps on your iPhone, iPad, or iPod touch. It will also be helpful if you familiarize yourself thoroughly with the Xcode development environment.
Next, you need to import Apple's Accessory Framework. To do this, click the Project in the left pane, then choose Build Phases, and open the "Link Binary With" section. Click +, locate the ExternalAccessory.framework, and add it.
Step #9: Add some declarations to the view controller
This step is optional, but it will avoid the problem of you seeing an error message ("This accessory requires an application...") each time you plug in the cable.
In Xcode, expand the Supporting Files group and click on Hello-Arduino.plist to open it.
Right-click the bottom row, and choose Add Row. Click the up/down pointing arrows to the right of the new row's key (it will probably default to "Application Category") and choose "Supported external accessory protocols".
Click the triangle to the left of the key name you just selected to open up the list. In the value field for Item 0, type com.redpark.hobdb9.
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