I added version to my DataModel and got "cdtool can not compile".
Did anyone experience similar problem? and what is "cdtool" ?
The problem was that I my data model contains many-to-many relationship without the inverse of it.
From Apple documentation:
You must define many-to-many relationships in both directions—that is, you must specify two relationships, each being the inverse of the other. You can’t just define a to-many relationship in one direction and try to use it as a many-to-many. If you do, you will end up with referential integrity problems.