核心数据关系是否在现实世界中使用？

I'm very familiar with Core Data but I haven't found any practical use for Core Data relationships. I know conceptually what they should do but they don't seem to enforce anything. Standard concepts such as primary/foreign key, cascading deletes, deleting a value you shouldn't be able to because of relationship constraints don't seem to be enforced.I'm very familiar with Core Data but I haven't