Are there any security guidelines for development and assessment of (native) iPhone applications?
See also Android API/development security pitfalls. Many of the issues mentioned there are applicable to iPhone applications, too: e.g., insufficient protection of data in transit or in storage, insufficiently cautious handling of data from untrusted sources, risks from imperfect isolation of apps.
Here are five suggested guidelines for iPhone application development and security considerations. In general you'll find them to be the same as security for any application development. http://intrepidusgroup.com/insight/2010/05/top-5-iphone-application-development-security-issues/