Programming in Objective-C
Programming in Objective-C is a concise, carefully written tutorial on the basics of Objective-C and object-oriented programming. The book makes no assumption about prior experience with object-oriented programming languages or with the C language (upon which Objective-C is based). And because of this, both novice and experienced programmers alike can use this book to quickly and effectively learn the fundamentals of Objective-C.
Using a gcc predefined macro, DATE, the code can know for itself when it was compiled, and build in an expiration date based on that value.
The former code (http://snipplr.com/view/3448/kill-app-after-expire-date/) was not internationalised and might cause an issue when run outside of English speaking countries. This code resolves the locale issue.