With swift 2.1 and CoreData, I want to delete all data of my database.
with following way, it works well
let context = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext
let request = NSFetchRequest(entityName: "UserCourse")
let arr = try! context.executeFetchRequest(request)
for item in arr{
context.deleteObject(item as! NSManagedObject)
try! context.save()
}
but i heard that there is a better way to do that with
NSBatchDeleteRequest
here is the code
let context = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext
let model = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectModel
let delete = NSBatchDeleteRequest(fetchRequest: NSFetchRequest(entityName: "Data"))
let coordinator = NSPersistentStoreCoordinator(managedObjectModel: model)
try! coordinator.executeRequest(delete, withContext: context)
but it raise an error said
2015-12-10 01:36:21.195 test[1090:40088] CoreData: error: Illegal attempt to save to a file that was never opened. "This NSPersistentStoreCoordinator has no persistent stores (unknown). It cannot perform a save operation.". No last error recorded.
2015-12-10 01:36:21.202 test[1090:40088] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'This NSPersistentStoreCoordinator has no persistent stores (unknown). It cannot perform a save operation.'
I wonder there must be something wrong with the model or coordinator, but I can't figure out how to get a correct coordinator instance, someone can help me?
This line:
let coordinator = NSPersistentStoreCoordinator(managedObjectModel: model)
creates a new persistentStoreCoordinator, associated with your model, but does not link it to a persistentStore. Hence the error message.
I suspect actually need to use the existing persistentStoreCoordinator associated with your context:
let coordinator = context.persistentStoreCoordinator
Related
I am reading bunch of objects from core data store , when I am trying to read object from this array in later part of code Xcode asserts for wrong thread access on that statement. I have added -com.apple.CoreData.ConcurrencyDebug 1 flag to the scheme to find out issues related to core data concurrency . When I remove this flag everything works fine.
Here is how I read the data from core data store
let managedContext =
appDelegate.persistentContainer.newBackgroundContext()
//setup request to load persons ( cached contacts)
let fetchRequest =
NSFetchRequest<NSManagedObject>(entityName: "Person")
fetchRequest.fetchBatchSize = 20
//read entties
managedContext.performAndWait {
do {
self.people = try managedContext.fetch(fetchRequest)
print("\(self.people.count) contacts retrieved from cache(CD)" )
} catch let error as NSError {
print("Could not fetch. \(error), \(error.userInfo)")
}
}
And I am reading the array from other part of code as below
let tempContact = self.people[index]
var property = tempContact.value(forKey: "firstName") as! String
I get assertion on second line above. The above code resides inside a function which I have tried calling as below
let appDelegate = UIApplication.shared.delegate as! AppDelegate
let moc = appDelegate.persistentContainer.viewContext
let privateMOC = NSManagedObjectContext(concurrencyType: .privateQueueConcurrencyType)
privateMOC.parent = moc
privateMOC.perform {
self.updateChangedContacts()
}
self.contactsTableView.reloadData()
If I simply call updateChangedContacts directly it works , but if I have large number of contacts this operation is going to take significant time blocking main UI.
I want to avoid that , how can i approach this ?
Good morning,
I'm working for the first time using CoreData with Swift 2.2. At the moment, I can add objects to my entity "Item" and I can remove all the items after I press a button "Remove everything". That's correct, but when I delete all the objects and then I restart my app, I still have the same Core Data before the "Remove everything" action.
That's how I delete the Core Data objects:
#IBAction func removeWishlist(sender: AnyObject) {
deleteAllData("ItemsWishlist")
getWishlist()
self.tableView.reloadData()
}
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)
print("Deleted")
}
} catch let error as NSError {
print(error)
}
}
And it's working because when I press the button, the list is empty, but when I restart the app, it shows again the same items as before I pressed the "clear" button.
And that's my AppDelegate with the Core Data part:
// MARK: - Core Data stack
lazy var applicationDocumentsDirectory: NSURL = {
// The directory the application uses to store the Core Data store file. This code uses a directory named "-.test" in the application's documents Application Support directory.
let urls = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)
return urls[urls.count-1]
}()
lazy var managedObjectModel: NSManagedObjectModel = {
// The managed object model for the application. This property is not optional. It is a fatal error for the application not to be able to find and load its model.
let modelURL = NSBundle.mainBundle().URLForResource("wishlist", withExtension: "momd")!
return NSManagedObjectModel(contentsOfURL: modelURL)!
}()
lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator = {
// The persistent store coordinator for the application. This implementation creates and returns a coordinator, having added the store for the application to it. This property is optional since there are legitimate error conditions that could cause the creation of the store to fail.
// Create the coordinator and store
let coordinator = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
let url = self.applicationDocumentsDirectory.URLByAppendingPathComponent("SingleViewCoreData.sqlite")
var failureReason = "There was an error creating or loading the application's saved data."
do {
try coordinator.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: url, options: nil)
} catch {
// Report any error we got.
var dict = [String: AnyObject]()
dict[NSLocalizedDescriptionKey] = "Failed to initialize the application's saved data"
dict[NSLocalizedFailureReasonErrorKey] = failureReason
dict[NSUnderlyingErrorKey] = error as NSError
let wrappedError = NSError(domain: "YOUR_ERROR_DOMAIN", code: 9999, userInfo: dict)
// Replace this with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
NSLog("Unresolved error \(wrappedError), \(wrappedError.userInfo)")
abort()
}
return coordinator
}()
lazy var managedObjectContext: NSManagedObjectContext = {
// Returns the managed object context for the application (which is already bound to the persistent store coordinator for the application.) This property is optional since there are legitimate error conditions that could cause the creation of the context to fail.
let coordinator = self.persistentStoreCoordinator
var managedObjectContext = NSManagedObjectContext(concurrencyType: .MainQueueConcurrencyType)
managedObjectContext.persistentStoreCoordinator = coordinator
return managedObjectContext
}()
// MARK: - Core Data Saving support
func saveContext () {
if managedObjectContext.hasChanges {
do {
try managedObjectContext.save()
} catch {
// Replace this implementation with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
let nserror = error as NSError
NSLog("Unresolved error \(nserror), \(nserror.userInfo)")
abort()
}
}
}
What am I doing wrong with the Core Data? How can I resolve this issue?
Much appreciated,
Regards.
The reason why you got those objects back after restarting your app is because you did not save your NSManagedObjectContext after performing all the deletion so that those changes can be persisted to the persistence store you are using.
The context is like a virtual board. Think of your managed objects on a context as toys that you put on a table to play with. You can move them around, break them, move them out of the table, and bring new toys in. That table is your managed object context, and you can save its state when you are ready. When you save the state of the managed object context, this save operation will be communicated to the persistent store coordinator to which the context is connected. Then the persistent store coordinator will store the information to the persistent store and subsequently to disk.
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)
print("Deleted")
}
} catch let error as NSError {
print(error)
}
appDelegate.saveContext()
}
For performance benefits, you should look into NSBatchDeleteRequest.
I am trying to implement CoreData with my existing swift project. I followed this tutorial and implemented it with UITableView.
The data is getting added contentiously to the data model (from another view controller) when I am fetching data model record (in another view controller).
Problem
Navigating to the View Controller with UITableView, shows data from data model once. Tapping on the tableView or sliding it up or down causing the application to crash with error
Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Entity name must not be nil.'
Function for saving record :
func saveData(date: String, usr : String, piid: String, healthD:String, temp:String, humd:String) {
//1
let managedContext = DataController().managedObjectContext
//2
let entity = NSEntityDescription.entityForName("Hygeine",
inManagedObjectContext:managedContext)
let health = NSManagedObject(entity: entity!,
insertIntoManagedObjectContext: managedContext)
//3
health.setValue(date, forKey: "date")
health.setValue(healthD, forKey: "health")
health.setValue(temp, forKey: "temp")
health.setValue(humd, forKey: "humd")
health.setValue(piid, forKey: "pi_id")
health.setValue(usr, forKey: "usr")
//4
do {
try managedContext.save()
//5
healthData.append(health)
} catch let error as NSError {
print("Could not save \(error), \(error.userInfo)")
}
}
ViewWillAppear for ViewController with UITableView :
override func viewWillAppear(animated: Bool) {
let managedContext = DataController().managedObjectContext
//2
let fetchRequest = NSFetchRequest(entityName: "Hygeine")
//3
do {
let results =
try managedContext.executeFetchRequest(fetchRequest)
healthData = results as! [NSManagedObject]
} catch let error as NSError {
print("Could not fetch \(error), \(error.userInfo)")
}
}
There are a lot of Objective-C solution to this problem but how to solve it in Swift 2. What I am doing wrong here ?
entityForName returns an optional that you are force unwrapping. That is most likely your error and easily caught in the debugger.
Is your entity name entered wrong? Check it against your model.
And as others have said, learn NSFetchedResultsController, while it won't solve this error, it is easier to work with when dealing with a UITableViewController.
Before deleteData() method was called, I've verified that there are two instances in my Core Data. Now I need to delete one away. I referred to this tutorial to delete my core data.
I managed to copy the first NSManagedObject instance through let person = people[0] as! NSManagedObject through this code, but app terminated on this line managedContext.delete(person).
The error faced was Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSManagedObjectContext delete:]: unrecognized selector sent to instance 0x7fefe28092e0'
func deleteData() {
var people = [Particulars]()
let fetchRequest = NSFetchRequest(entityName: "Particulars")
let appDel = UIApplication.sharedApplication().delegate as! AppDelegate
let managedContext = appDel.managedObjectContext
do {
people = try managedContext.executeFetchRequest(fetchRequest) as! [Particulars]
do {
let person = people[0] as! NSManagedObject
managedContext.delete(person)
try managedContext.save()
} catch let error as NSError {
print("Could not delete data \(error)")
}
} catch let error as NSError
{
print("Could not fetch data \(error)")
}
}
The proper call is not delete, but deleteObject for NSManagedObjectContext.
Also note that it is more readable to write person.first rather than people[0], but it is of course a matter of taste.
I think let person = people[0] as! NSManagedObject is problematic, because
It is not safe and would crash if there are no search results. Use if let person = people.first...
The downcast from Particulars to NSManagedObject also does not make sense. You have already performed a cast when getting the search results.
I am making a sprite kit game and need to save three integers: currentLevel, maxLevelReached and highScore. I would also like to implement those to iCloud, but thats another step for me, first I want to figure out the problems I have right now. Basically, I am trying to use core data to store those. In my app delegate I added the following (basically I created new project and copied core data code)
// MARK: - Core Data stack
lazy var applicationDocumentsDirectory: NSURL = {
let urls = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)
return urls[urls.count-1] as! NSURL
}()
lazy var managedObjectModel: NSManagedObjectModel = {
let modelURL = NSBundle.mainBundle().URLForResource("GameState", withExtension: "momd")!
return NSManagedObjectModel(contentsOfURL: modelURL)!
}()
lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator? = {
var coordinator: NSPersistentStoreCoordinator? = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
let url = self.applicationDocumentsDirectory.URLByAppendingPathComponent("APPNAME.sqlite")
var error: NSError? = nil
var failureReason = "There was an error creating or loading the application's saved data."
if coordinator!.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: url, options: nil, error: &error) == nil {
coordinator = nil
// Report any error we got.
var dict = [String: AnyObject]()
dict[NSLocalizedDescriptionKey] = "Failed to initialize the application's saved data"
dict[NSLocalizedFailureReasonErrorKey] = failureReason
dict[NSUnderlyingErrorKey] = error
error = NSError(domain: "YOUR_ERROR_DOMAIN", code: 9999, userInfo: dict)
NSLog("Unresolved error \(error), \(error!.userInfo)")
abort()
}
return coordinator
}()
lazy var managedObjectContext: NSManagedObjectContext? = {
let coordinator = self.persistentStoreCoordinator
if coordinator == nil {
return nil
}
var managedObjectContext = NSManagedObjectContext()
managedObjectContext.persistentStoreCoordinator = coordinator
return managedObjectContext
}()
// MARK: - Core Data Saving support
func saveContext () {
if let moc = self.managedObjectContext {
var error: NSError? = nil
if moc.hasChanges && !moc.save(&error) {
// Replace this implementation with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
NSLog("Unresolved error \(error), \(error!.userInfo)")
abort()
}
}
}
when I did that, I created my data model (File->new->CoreData->Data model) and named it GameState. I then created the entity called CurrentLevel and added attribute of type Int16 and name currentLevel. I made the entity of class Appname.CurrentLevel. Then, in my game scene I added the following properties:
var currentLevel = [NSManagedObject]()
var levelToShow: Int16!
And created these two functions to handle core data stuff.
//Handling the fetching from the CoreData
func fetchTheStuff() {
//1
let appDelegate =
UIApplication.sharedApplication().delegate as! AppDelegate
let managedContext = appDelegate.managedObjectContext!
//2
let fetchRequest = NSFetchRequest(entityName:"CurrentLevel")
//3
var error: NSError?
let fetchedResults =
managedContext.executeFetchRequest(fetchRequest,
error: &error) as? [NSManagedObject]
if let results = fetchedResults {
currentLevel = results
println(currentLevel)
} else {
println("Could not fetch \(error), \(error!.userInfo)")
}
}
//Handling the saving
func saveCurrentLevel(cLevel: Int16){
let appDelegate =
UIApplication.sharedApplication().delegate as! AppDelegate
let managedContext = appDelegate.managedObjectContext!
let entity = NSEntityDescription.entityForName("CurrentLevel",
inManagedObjectContext:
managedContext)
let curLevel = NSManagedObject(entity: entity!,
insertIntoManagedObjectContext:managedContext)
curLevel.setValue(name, forKey: "currentLevel")
var error: NSError?
if !managedContext.save(&error) {
println("Could not save \(error), \(error?.userInfo)")
}
}
As you can see the fetch function is still in testing stage (I am simply printing the results). If I fetch it the first time I use the app, it gives me an empty string, as it should be. However, If I try to save a number using save function and then fetch the stuff, the log screen gives me the following warning:
CoreData: warning: Unable to load class named 'appname.CurrentLevel' for entity 'CurrentLevel'. Class not found, using default NSManagedObject instead.
Knowing the function I want to achieve, seeing the method I (try) to use, does anyone know how to solve my problem?
P.S. Also, it seems that this whole core data stuff is quite complicated, I have a hard time grasping how exactly it works even though I read a quite a lot about it. So if anyone has a suggestion on decreasing the complexity to achieve the same result (hence, not using any of the functionality) , tips are more than welcome.
Answer to the initial question
Please make sure, to generate the correct classes for your Coredata Model, highlighting your entities and then chosing Editor -> Create NSObject subclass