A Swift playground demonstrating that deleting an NSManagedObject causes a fault to fire

ManagedObjectDeletionFiringFault.swift

import CoreData
import PlaygroundSupport

// Build a simple model in code for demo purposes.
// The model has a single entity called "Entity" with a single optional string attribute called "testAttribute".
// There are no relationships in the model.
let model = NSManagedObjectModel()
let entity = NSEntityDescription()
entity.name = "Entity"
let testAttribute = NSAttributeDescription()
testAttribute.name = "testAttribute"
testAttribute.attributeType = .stringAttributeType
testAttribute.isOptional = true
entity.properties = [testAttribute]
model.entities = [entity]

print("Model: \(model)")


let container = NSPersistentContainer(name: "TestModel", managedObjectModel: model)
container.loadPersistentStores{ _,_ in
    
    // Create a new entity, save the model and reset the context
    let context = container.viewContext
    let entity = NSEntityDescription.insertNewObject(forEntityName: "Entity", into: context)
    entity.setValue("test", forKey: "testAttribute")
    try! context.save()
    context.reset()
    
    // Now try to fetch the existing entity. We want to delete it without firing the fault
    let f = NSFetchRequest<NSManagedObject>(entityName: "Entity")
    f.includesPropertyValues = false
    f.fetchLimit = 1
    
    // Get the first result from the fetch. This will be a fault
    let firstEntity = try! context.fetch(f).first!
    print("Entity is fault: \(firstEntity.isFault)")
    
    // Delete the object. It will no longer be a fault
    context.delete(firstEntity)
    print("Entity is fault: \(firstEntity.isFault)")
}

PlaygroundPage.current.needsIndefiniteExecution = true