I just bought the XCode 4 version of this: http://www.techotopia.com/index.php/IPhone_iOS_4_Development_Essentials_Xcode_4_Edition I'm on chapter 15 where I get several warnings and an error. The warnings: Incomplete implementation of class '*' Incomplete implementation of class 'TableExampleViewController' the error is on startup and says SIGABRT, If I disconnect the dataSource and delegate, the app will run, If I connect them per the book, it crashes. The chapter is basically setting up a simple Table View, and using an array to load the data. I think they left something out of the book. The '*' related warning seems to be a syntax error / typing error, but I can't seem to see it. The SIGABRT seems to be related to the connection of the dataSource, which is an NSArray and set to File's Owner (as is delegate) The website that sells the book also offers it for free online, I bought it last night and see no way to contact them or get source code. On the up side, all the other examples are working fine.