iOS: Delete ALL Core Data Swift
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 following:
let appDel: foodforteethAppDelegate = UIApplication.sharedApplication().delegate as foodforteethAppDelegate
let context: NSManagedObjectContext = appDel.managedObjectContext
Then I've messed around with various methods to try and delete all the core data content but I can't seem to get it to work. I've used removeAll to delete from a stored array but still can't delete from the core data. I assume I need some type of for loop but unsure how to go about making it from the request.
I have tried applying the basic principle of deleting a single row
func tableView(tableView: UITableView!, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath!) {
let appDel: foodforteethAppDelegate = UIApplication.sharedApplication().delegate as foodforteethAppDelegate
let context:NSManagedObjectContext = appDel.managedObjectContext
if editingStyle == UITableViewCellEditingStyle.Delete {
if let tv = tblTasks {
context.deleteObject(myList[indexPath!.row] as NSManagedObject)
myList.removeAtIndex(indexPath!.row)
tv.deleteRowsAtIndexPaths([indexPath!], withRowAnimation: UITableViewRowAnimation.Fade)
}
var error: NSError? = nil
if !context.save(&error) {
abort()
}
}
}
However, the issue with this is that when I click a button, I don't have the indexPath value and also I need to loop through all the values which I can't seem to do with context.
Try this simple solution:
func deleteAllData(entity: String)
{
let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
let managedContext = appDelegate.managedObjectContext
let fetchRequest = NSFetchRequest(entityName: entity)
fetchRequest.returnsObjectsAsFaults = false
do
{
let results = try managedContext.executeFetchRequest(fetchRequest)
for managedObject in results
{
let managedObjectData:NSManagedObject = managedObject as! NSManagedObject
managedContext.deleteObject(managedObjectData)
}
} catch let error as NSError {
print("Detele all data in \(entity) error : \(error) \(error.userInfo)")
}
}
Swift 4
func deleteAllData(_ entity:String) {
let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: entity)
fetchRequest.returnsObjectsAsFaults = false
do {
let results = try dataController.viewContext.fetch(fetchRequest)
for object in results {
guard let objectData = object as? NSManagedObject else {continue}
dataController.viewContext.delete(objectData)
}
} catch let error {
print("Detele all data in \(entity) error :", error)
}
}
Implementation:
self.deleteAllData("your_entityName")
You can use destroyPersistentStore
starting in iOS 9.0 and Swift 3:
public func clearDatabase() {
guard let url = persistentContainer.persistentStoreDescriptions.first?.url else { return }
let persistentStoreCoordinator = persistentContainer.persistentStoreCoordinator
do {
try persistentStoreCoordinator.destroyPersistentStore(at:url, ofType: NSSQLiteStoreType, options: nil)
try persistentStoreCoordinator.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: url, options: nil)
} catch {
print("Attempted to clear persistent store: " + error.localizedDescription)
}
}
To Delete all data you can use NSBatchDeleteRequest
func deleteAllData(entity: String)
{
let ReqVar = NSFetchRequest(entityName: entity)
let DelAllReqVar = NSBatchDeleteRequest(fetchRequest: ReqVar)
do { try ContxtVar.executeRequest(DelAllReqVar) }
catch { print(error) }
}
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
For Swift 3.0
func DeleteAllData(){
let appDelegate = UIApplication.shared.delegate as! AppDelegate
let managedContext = appDelegate.persistentContainer.viewContext
let DelAllReqVar = NSBatchDeleteRequest(fetchRequest: NSFetchRequest<NSFetchRequestResult>(entityName: "Entity"))
do {
try managedContext.execute(DelAllReqVar)
}
catch {
print(error)
}
}