问题
I've been trying to get my head around adding objects in relationships using CoreData and Swift. I am at a loss, I do not understand why my code does not work. I am trying to add an "Event" to a "Team". I can not find the difference between accepted answers (that should work), and my code (that does not).
Teams.swift:
import Foundation
import CoreData
class Teams: NSManagedObject {
@NSManaged var teamName: String
@NSManaged var matches: NSSet
}
extension Teams {
func addEventToTeam(event:Event) {
//self.mutableSetValueForKeyPath("matches").addObject(event)
var matchez: NSMutableSet
matchez = self.mutableSetValueForKey("matches")
matchez.addObject(event)
//var manyRelation = self.valueForKeyPath("matches") as NSMutableSet
//manyRelation.addObject(event)
}
func getTeamName() -> String {
return teamName
}
}
Calling code (from configure view):
import UIKit
import CoreData
class DetailViewController: UIViewController, NSFetchedResultsControllerDelegate {
var managedObjectContext: NSManagedObjectContext? = nil
@IBOutlet weak var detailDescriptionLabel: UILabel!
var detailItem: AnyObject? {
didSet {
// Update the view.
self.configureView()
}
}
func configureView() {
// Update the user interface for the detail item.
if let detail: Event = (self.detailItem as? Event) {
//if let detail: AnyObject = self.detailItem {
if let label = self.detailDescriptionLabel {
label.text = detail.valueForKey("timeStamp").description
self.insertNewObject(self);
label.text = String(detail.getNumberOfTeams())
//detail.getTeams().
var hej: Array<Teams>
hej = detail.getTeams()
label.text = "tjosan"
for tmpTeam : Teams in hej {
label.text = label.text + ", " + tmpTeam.getTeamName()
}
}
}
if true {
}
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
self.configureView()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
var fetchedResultsController: NSFetchedResultsController {
if _fetchedResultsController != nil {
return _fetchedResultsController!
}
let fetchRequest = NSFetchRequest()
// Edit the entity name as appropriate.
let team = NSEntityDescription.entityForName("Teams", inManagedObjectContext: self.managedObjectContext)
fetchRequest.entity = team
// Set the batch size to a suitable number.
fetchRequest.fetchBatchSize = 20
// Edit the sort key as appropriate.
let sortDescriptor = NSSortDescriptor(key: "teamName", ascending: false)
let sortDescriptors = [sortDescriptor]
fetchRequest.sortDescriptors = [sortDescriptor]
// Edit the section name key path and cache name if appropriate.
// nil for section name key path means "no sections".
let aFetchedResultsController = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: self.managedObjectContext, sectionNameKeyPath: nil, cacheName: "Master")
aFetchedResultsController.delegate = self
_fetchedResultsController = aFetchedResultsController
var error: NSError? = nil
if !_fetchedResultsController!.performFetch(&error) {
// Replace this implementation with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
//println("Unresolved error \(error), \(error.userInfo)")
abort()
}
return _fetchedResultsController!
}
var _fetchedResultsController: NSFetchedResultsController? = nil
func insertNewObject(sender: AnyObject) {
let context = self.fetchedResultsController.managedObjectContext
let team = self.fetchedResultsController.fetchRequest.entity
let newManagedObject = NSEntityDescription.insertNewObjectForEntityForName(team.name, inManagedObjectContext: context) as Teams
// If appropriate, configure the new managed object.
// Normally you should use accessor methods, but using KVC here avoids the need to add a custom class to the template.
newManagedObject.setValue("Lagur Namnurk", forKey: "teamName")
newManagedObject.addEventToTeam(self.detailItem as Event)
// Save the context.
var error: NSError? = nil
if !context.save(&error) {
// Replace this implementation with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
//println("Unresolved error \(error), \(error.userInfo)")
abort()
}
}
}
Error message:
2014-08-13 18:38:46.651 Score Calculator 2[10538:829319] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSSet intersectsSet:]: set argument is not an NSSet'
*** First throw call stack:
(
0 CoreFoundation 0x00000001028a53e5 __exceptionPreprocess + 165
1 libobjc.A.dylib 0x00000001043b8967 objc_exception_throw + 45
2 CoreFoundation 0x000000010280fc6c -[NSSet intersectsSet:] + 940
3 Foundation 0x0000000102d0c4a6 NSKeyValueWillChangeBySetMutation + 156
4 Foundation 0x0000000102c804fa NSKeyValueWillChange + 386
5 Foundation 0x0000000102d0c3fb -[NSObject(NSKeyValueObserverNotification) willChangeValueForKey:withSetMutation:usingObjects:] + 310
6 CoreData 0x00000001024178d7 -[NSManagedObject(_NSInternalMethods) _includeObject:intoPropertyWithKey:andIndex:] + 551
7 CoreData 0x0000000102418294 -[NSManagedObject(_NSInternalMethods) _maintainInverseRelationship:forProperty:forChange:onSet:] + 276
8 CoreData 0x0000000102416ef2 -[NSManagedObject(_NSInternalMethods) _didChangeValue:forRelationship:named:withInverse:] + 562
9 Foundation 0x0000000102c835d6 NSKeyValueNotifyObserver + 356
10 Foundation 0x0000000102c827fd NSKeyValueDidChange + 466
11 Foundation 0x0000000102d0c7ee -[NSObject(NSKeyValueObserverNotification) didChangeValueForKey:withSetMutation:usingObjects:] + 118
12 CoreData 0x00000001024180b0 -[NSManagedObject didChangeValueForKey:withSetMutation:usingObjects:] + 80
13 CoreData 0x000000010242fa11 -[_NSNotifyingWrapperMutableSet addObject:] + 161
edit: a couple of clarifications. Teams and Event have a multi-to-multi, unordered relationship.
回答1:
Yesss!! I found the answer!
I had created a new function in the class Events.swift (the other side of the relationship).
I had written the following code:
import Foundation
import CoreData
class Event: NSManagedObject {
@NSManaged var timeStamp: NSDate
@NSManaged var teams: NSSet
}
extension Event {
func addTeamToEvent(team:Teams) {
var teamz = self.mutableSetValueForKey("teams")
teamz.addObject(team)
}
func getNumberOfTeams() -> Int {
return self.teams.count;
}
func getTeams() -> [Teams] {
var tmpsak: [Teams]
tmpsak = self.teams.allObjects as [Teams]
tmpsak = self.teams.allObjects as [Teams]
return tmpsak
}
}
which I thought was unrelated. However, renaming getTeams to getTeamsAsArray removed the problem. I am guessing that CoreData, when filling in the other end of the relationship, uses a built-in function called getTeams() (since the other class was called Teams). I accidentally overrode(?) it, causing it to fail.
Thank you for your suggestions, and I hope this can be helpful to someone else!
On a somewhat related note, a bug with similar symptoms was identified a few years ago (and appears to still be present), that shows itself in auto-generated code when using ordered many-to-many relationships.
回答2:
If you use the objective C generated NSManagedObject subclasses, they include custom methods for adding a single object - I think these are tried and tested and seem better than what is currently there for swift.
Theoretically you would just need to just set the new set with whatever new set you created. One option would be:
var matchobjs = matches.allObjects as [Event]
matchobjs.append(event)
matches = NSSet(array: matchobjs)
However the error looks very similar to this post:
Which to me looks like theres something fishy going on again with many-to-many relationships...
来源：https://stackoverflow.com/questions/25291760/swift-and-coredata-problems-with-relationship-nsset-nsset-intersectsset