I finally found the answer to this problem. It comes from the way I was setting
the relationship. I was calling:
[[expense valueForKey:@"tags"] addObject:tag];
..which apparently is too direct. What I need is something more like:
[[expense mutableSetValueForKey:@"tags"] addObject:tag];
I
In my finance app, I have Expense and Tag entities with many-to-many
relationships to each other. But changing those relationships doesn't mark the
document as dirty, and the changes don't get saved. It doesn't seem to matter
if the relationships are optional or not, and they're not transient. T
