Swift 3 Core Data Delete Object

Question

Unfortunately the new Core Data semantics make me crazy. My previous question had a clean code that didn\'t work because of incorrect auto generation of header files. Now I

Answer 1

Delete the object from core data

let entity = NSEntityDescription.entity(forEntityName: "Students", in: managedContext)
        let request = NSFetchRequest<NSFetchRequestResult>()
        request.entity = entity
        if let result = try? managedContext.fetch(request) {
            for object in result {
                managedContext.delete(object as! NSManagedObject)
            }
            txtName.text = ""
            txtPhone.text = ""
            txt_Address.text = ""
            labelStatus.text = "Deleted"

        }

Answer 2

The trick here, it is save context after deleting your objects.

let fetchRequest: NSFetchRequest<Profile> = Profile.fetchRequest()
fetchRequest.predicate = Predicate.init(format: "profileID==\(withID)")
let objects = try! context.fetch(fetchRequest)
for obj in objects {
    context.delete(obj)
}

do {
    try context.save() // <- remember to put this :)
} catch {
    // Do something... fatalerror
}

I hope this can help someone.

Answer 3

Delete Core Data Object with query in Swift 5, 4.2

let fetchrequest = NSFetchRequest<Your_Model>(entityName: "Your_Entity_Name")
fetchrequest.predicate = NSPredicate(format: "any your_key == %d", your_value)

hope this will help to someone

Answer 4

The result of a fetch is an array of managed objects, in your case [Event], so you can enumerate the array and delete all matching objects. Example (using try? instead of try! to avoid a crash in the case of a fetch error):

if let result = try? context.fetch(fetchRequest) {
    for object in result {
        context.delete(object)
    }
}

If no matching objects exist then the fetch succeeds, but the resulting array is empty.

---

Note: In your code, object has the type [Event] and therefore in

context.delete(object)

the compiler creates a call to the

public func delete(_ sender: AnyObject?)

method of NSObject instead of the expected

public func delete(_ object: NSManagedObject)

method of NSManagedObjectContext. That is why your code compiles but fails at runtime.

Answer 5

Swift 4 without using string for Entity

let fetchRequest: NSFetchRequest<Profile> = Profile.fetchRequest()
fetchRequest.predicate = Predicate.init(format: "profileID==\(withID)")

do {
    let objects = try context.fetch(fetchRequest)
    for object in objects {
        context.delete(object)
    }
    try context.save()
} catch _ {
    // error handling
}

Answer 6

func deleteRecords() {
    let delegate = UIApplication.shared.delegate as! AppDelegate
    let context = delegate.persistentContainer.viewContext

    let deleteFetch = NSFetchRequest<NSFetchRequestResult>(entityName: "nameofentity")
    let deleteRequest = NSBatchDeleteRequest(fetchRequest: deleteFetch)

    do {
        try context.execute(deleteRequest)
        try context.save()
    } catch {
        print ("There was an error")
    }
}