I have been trying to wrap my arms around Core Data this past week. I found some simple examples on the Web and in Apples documentation and all went reasonably well considering that it is one of the more complicated parts of the SDK. But the wheels came off as I tried to dig in deeper. I have a reasonably complicated data model and so decided to buy the “More iPhone 3 Development” book by Dave Mark & Jeff LaMarche Woes. I had used their first book “Beginning iPhone Development” to learn iPhone development and it was absolutely invaluable. Book two arrived here a few minutes ago thanks to Amazon Prime, but being impatient I had already downloaded the sample code from their forum. I immediately jumped in and ran a few of their sample apps for core data and I am sorry to say that I was disappointed as the Core Data apps kept on crashing. I tried to dig around and find the cause of the errors but not luck. Quite a disappointment as the code has been written in a generic way to handle any data model. I have posted the error on the forum and hopefully it will be answered soon.