iOS: Delete ALL Core Data Swift

Question

I am a little confused as to how to delete all core data in swift. I have created a button with an IBAction linked. On the click of the button I have the follow

Answer 1

In Swift UI

when you select core data at the beginning of project the persistence coordinator is automatically created by swift in app delegate. The scene delegate creates @environmentObject for managed context

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

let contentView = ContentView().environment(\.managedObjectContext, context)

create instance of manageObjectContext in content view and also fetchRequest object using property wrapper @FetchRequest

@Environment(\.managedObjectContext) var moc
@FetchRequest(entity: EntityName.entity(), sortDescriptors: []) var entityNames: FetchedResults<EntityName>

For delete action perform

for entityName in entityNames {
moc.delete(entityName)
}
try? moc.save()

try operation can throw error so please implement do try catch block in production code to handle error properly.

Answer 2

Swift 3

// Replace 'MyEntityName' with your managed object class.
let moc = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
let fetchRequest: NSFetchRequest<MyEntityName> = MyEntityName.fetchRequest()
fetchRequest.returnsObjectsAsFaults = false
moc.perform {
    do {
        let myEntities = try fetchRequest.execute()
        for myEntity in myEntities {
            moc.delete(myEntity)
        }
        try moc.save()
    } catch let error {
        print("Delete Error: \(error.localizedDescription)")
    }
}

Answer 3

For Swift 4.0

  func deleteAllData(_ entity:String) {

    let managedContext =  DatabaseController.getContext().persistentStoreCoordinator
     let context = DatabaseController.getContext()
    let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: entity)
    let batchDeleteRequest = NSBatchDeleteRequest(fetchRequest: fetchRequest)
    do {
        try managedContext?.execute(batchDeleteRequest, with: context)
    }
    catch {
        print(error)
    }


  }

Answer 4

static func fetch<T>(entity: T.Type, withPredicate predicate: NSPredicate? = nil) -> Array<T>? where T : NSManagedObject {
    let request: NSFetchRequest<T> = NSFetchRequest<T>(entityName: String(describing: T.self))
    request.predicate = predicate
    do {
        return try context.fetch(request)
    }catch{
        print(error.localizedDescription)
    }
    return nil
}

 static func delete<T>(_ object: T) where T : NSManagedObject {
    context.delete(object)
    saveContext()
}

static func reset<T>(entity: T.Type) where T : NSManagedObject {
    fetch(entity: entity.self)?.forEach{
        delete($0)
    }

}

Answer 5

Try this:

func deleteAllData(entity: String)
{
    let appDelegate = UIApplication.shared.delegate as! AppDelegate
    let context = appDelegate.persistentContainer.viewContext
    let ReqVar = NSFetchRequest(entityName: entity)
    let DelAllReqVar = NSBatchDeleteRequest(fetchRequest: ReqVar)
    do { try ContxtVar.executeRequest(DelAllReqVar) }
    catch { print(error) }
}