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

I have got it working using the following method:

@IBAction func btnDelTask_Click(sender: UIButton){

    let appDel: foodforteethAppDelegate = UIApplication.sharedApplication().delegate as foodforteethAppDelegate
    let context: NSManagedObjectContext = appDel.managedObjectContext  
    let request = NSFetchRequest(entityName: "Food")

    myList = context.executeFetchRequest(request, error: nil)


    if let tv = tblTasks {

        var bas: NSManagedObject!

        for bas: AnyObject in myList
        {
           context.deleteObject(bas as NSManagedObject)
        }

        myList.removeAll(keepCapacity: false)

        tv.reloadData()
        context.save(nil)
    }
}

However, I am unsure whether this is the best way to go about doing it. I'm also receiving a 'constant 'bas' inferred to have anyobject' error - so if there are any solutions for that then it would be great

EDIT

Fixed by changing to bas: AnyObject

Answer 2

An alternative can be to completely remove and recreate persistent store (iOS 10+, swift 3).

let urls = FileManager.default.urls(for: .libraryDirectory, in: .userDomainMask);
    var dbUrl = urls[urls.count-1];
    dbUrl = dbUrl.appendingPathComponent("Application Support/nameOfYourCoredataFile.sqlite")
    do {
        try persistentContainer.persistentStoreCoordinator.destroyPersistentStore(at: dbUrl, ofType: NSSQLiteStoreType, options: nil);
    } catch {
        print(error);
    }
    do {
        try persistentContainer.persistentStoreCoordinator.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: dbUrl, options: nil);
    } catch {
        print(error);
    }

Answer 3

Swift 4 :

destroyPersistentStoreAtURL(_:withType:options:) will delete (or truncate) the target persistent store. This will safely destroy a persistent store.

Add:

do {
    try persistentStoreCoordinator.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: persistentStoreURL, options: nil)
} catch {
    // Error Handling
}

Destroy / Delete / Truncate:

do {
    try persistentStoreCoordinator.destroyPersistentStoreAtURL(persistentStoreURL, withType: NSSQLiteStoreType, options: nil)
} catch {
    // Error Handling
}

Note : Parameters in above method should be identical to addPersistentStoreWithType method. You need to re-initiate storeCoordinator to use store again.

Answer 4

Swift 5

func deleteAllData(entity: String){

guard let appDelegate = UIApplication.shared.delegate as? AppDelegate else { return }
let managedContext = appDelegate.persistentContainer.viewContext
let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: entity)
fetchRequest.returnsObjectsAsFaults = false

do {
    let arrUsrObj = try managedContext.fetch(fetchRequest)
    for usrObj in arrUsrObj as! [NSManagedObject] {            
        managedContext.delete(usrObj)
    }
   try managedContext.save() //don't forget
    } catch let error as NSError {
    print("delete fail--",error)
  }

}

Answer 5

Here is my implementation to clear all core data in Swift 3, based on Jayant Dash's excellent (and comprehensive) answer. This is simpler due to only supporting iOS10+. It deletes all core data entities, without having to hardcode them.

public func clearAllCoreData() {
    let entities = self.persistentContainer.managedObjectModel.entities
    entities.flatMap({ $0.name }).forEach(clearDeepObjectEntity)
}

private func clearDeepObjectEntity(_ entity: String) {
    let context = self.persistentContainer.viewContext

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

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

Answer 6

For Swift 4.0 (modified version of svmrajesh's answer… or at least what Xcode turned it into before it would run it for me.)

func deleteAllData(entity: String) {
let appDelegate = UIApplication.shared.delegate as! AppDelegate
let managedContext = appDelegate.persistentContainer.viewContext
let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: entity)
fetchRequest.returnsObjectsAsFaults = false

do
{
    let results = try managedContext.fetch(fetchRequest)
    for managedObject in results
    {
        let managedObjectData:NSManagedObject = managedObject as! NSManagedObject
        managedContext.delete(managedObjectData)
    }
} catch let error as NSError {
    print("Delete all data in \(entity) error : \(error) \(error.userInfo)")
}
}

Implementation:

deleteAllData(entity: "entityName")