Swift 3 Core Data Delete Object

Swift 3 Core Data Delete Object

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)
    }
}

do {
    try context.save()
} catch {
    //Handle error
}

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.

Deleting all data in a Core Data entity in Swift 3

You're thinking of NSBatchDeleteRequest, which was added in iOS 9. Create one like this:

let fetch = NSFetchRequest<NSFetchRequestResult>(entityName: "Employee")
let request = NSBatchDeleteRequest(fetchRequest: fetch)

You can also add a predicate if you only wanted to delete instances that match the predicate. To run the request:

let result = try managedObjectContext.executeRequest(request)

Note that batch requests don't update any of your current app state. If you have managed objects in memory that would be affected by the delete, you need to stop using them immediately.

Core Data with SWIFT: How to delete object from Relationship entity?

Using predicates is exactly right. You'd want to set the predicate for the fetchRequest

let predicate = NSPredicate(format: "uniqueKey == %@", "value")
fetchRequest.predicate = predicate

Then you can delete the result

---

Related Topics