Master data passing objectID to another stream
I tried Google and searched SO thinking it would be pretty easy to find, but I'm surprised Swift didn't have examples of my problem.
I have multiple threads and from what I've read it is best to have a separate managed object context for each thread. If I want to access an object from a different context, I have to go around objectID
.
My question is, how do I pass an ID object to a context on a new thread?
Here's how to build my situation:
func doSomething(context: NSManagedObjectContext) {
let person = Persons(context: context) // NSManagedObject
dispatch_async(dispatch_get_global_queue(Int(QOS_CLASS_USER_INITIATED.value), 0)) {
let background = (UIApplication.sharedApplication().delegate as! AppDelegate).cdh.backgroundContext!
Birthdays(context: background, person) // NSManagedObject
saveContext(background)
}
}
Birthdays have individual relationships with people. If I execute this code it gives me an error:
Illegal attempt to establish a relationship 'person1' between objects in different contexts
Obviously because they are in separate contexts. So I tried to get the objectID person1
on let personsObjectID = person1.objectID
, but I don't know how I should use it to pass it to another thread. Any help is appreciated.
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It seems the only thing I needed to do was add:
let person = background.objectWithID(orders.objectID as! Persons
If I understand correctly, objectWithID
retrieves an object from storage and puts it into the context, returning a managed object. It would be nice if someone could check this if it's true.
func doSomething(context: NSManagedObjectContext) {
let person = Persons(context: context) // NSManagedObject
dispatch_async(dispatch_get_global_queue(Int(QOS_CLASS_USER_INITIATED.value), 0)) {
let background = (UIApplication.sharedApplication().delegate as! AppDelegate).cdh.backgroundContext!
let person = background.objectWithID(orders.objectID as! Persons
Birthdays(context: background, person) // NSManagedObject
saveContext(background)
}
}
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