IOS how to delete an object in core data swift

Question

The entity is "User" which has 2 attributes(email and password). I want to delete a User with the attribute email = "[email protected]". What do I do? I did this far, but I don't know how to delete with attribute. Which means I need to locate the User first then make the delete.

    let appDel:AppDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
    let context:NSManagedObjectContext = appDel.managedObjectContext!
    context.deleteObject(User: NSManagedObject)
    context.save(nil)

Thank you in advance

You need to fetch user with desired name and password, then delete it by calling deleteObject method — Zell B.
– Zell B., Commented Aug 6, 2015 at 15:13

Fred Faust · Accepted Answer · 2015-08-06 15:18:32Z

9

You can use a predicate to limit your fetch to only return the object you want, then you can delete it, here's an example:

    let appDel  = UIApplication.sharedApplication().delegate as! AppDelegate
    let context = appDel.managedObjectContext!

    var fetchError : NSError?

    let fetchPredicate = NSPredicate(format: "email == %@", "[email protected]")

    let fetchUsers                      = NSFetchRequest(entityName: "User")
    fetchUsers.predicate                = fetchPredicate
    fetchUsers.returnsObjectsAsFaults   = false


    let fetchedUsers = context.executeFetchRequest(fetchUsers, error: &fetchError) as! [NSManagedObject]

    for fetchedUser in fetchedUsers {

        var deleteUserError: NSError?

        context.deleteObject(fetchedUser)
        context.save(&deleteUserError)
    }

answered Aug 6, 2015 at 15:18

Fred Faust

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1 Comment

sekaisan Over a year ago

This works and it's quite clear to understand. Thank you.

slowlydeveloping · Accepted Answer · 2015-08-06 15:24:38Z

2

This should work:

    let managedObjectContext = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext
    let fetchRequest = NSFetchRequest(entityName: "User")
    if let fetchResults = try!managedObjectContext.executeFetchRequest(fetchRequest) as? [User] {
        for (var i=0; i<fetchResults.count; i++) {
            if fetchResults[i].email == "[email protected]" {
                managedObjectContext.deleteObject(fetchResults[i])
                try!managedObjectContext.save()
            }
        }
     }

answered Aug 6, 2015 at 15:24

slowlydeveloping

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