I am not an SQL DB programmer. One of the virtues of Core Data is that it is NOT SQL.
Hence, I am so surprised that there is such a dearth of documentation for one of the key technologies - NSPredicate - behind Core Data. “Core Data” devotes only one page, page 61 in my electronic version, to NSPredicate. (WoW, I am so disappointed that “Core Data” explains so little about this key technology. It really makes me lament purchasing “Core Data”.) Apple’s documentation, “Predicate Programming Guide”, recommended in “Core Data,” is just lame. It doesn’t address most of the NSPredicate keywords nor explains anything about how to make complex queries over to-many relationships. It does tell me that to-many queries, from a performance perspective, are an “expensive” operation. OK. That isn’t the same as telling me how to write NSPredicate join queries. What a missed opportunity for both the author and publisher of “Core Data”. Answering my query with “go learn SQL”, with SQL’s table centric model, is a dramatically poor answer for Core Data, with it’s object graph model. I am so disappointed in “Core Data”.
The Google is not terribly helpful. That is part of why I bought “Core Data”.
Please point me in a direction towards a decent NSPredicate reference.