Core Data NSPredicate fetch on entity relationship

问题:

I would like to be able to search the relationship of an entity using an IN clause. I have the following setup:

I would like to send over an array of nicknames and find all Persons associated with those nicknames.

//array of names to find
let nameArray: [String] = ["Tom", "Tommy", "Thomas"] 

// find all Persons who have a nickname associated with that person           
let predicate = NSPredicate(format: "ANY Person.nickName in %@",nameArray)
var fetch = NSFetchRequest(entityName: "Person")
fetch.predicate = predicate
var fetchError : NSError? = nil

// executes fetch
let results = context?.executeFetchRequest(fetch, error: &fetchError)

But when I run the code, I get the following error:

'NSInvalidArgumentException', reason: 'unimplemented SQL generation for predicate : (ANY Person.nickName IN {"Tom", "Tommy", "Thomas"})'

What am I doing wrong here? If I remove the predicate search, it returns all the results ok, but as soon as I add this line in, everything breaks.

回答1:

You should use the relationship name in your NSPredicate.
Try this:

let predicate = NSPredicate(format: "ANY personToNick.nickName in %@", nameArray)