I'm doing the following - but my app freezes when fetching the object:
[MagicalRecord saveWithBlock:^(NSManagedObjectContext *localContext) {
MyObject *myObject = [localContext objectWithID:objectID];
}];
I found some blogs mentioning dead locks with FetchRequests and nested contexts; but what can I do as an alternative here?
Thanks a lot,
Stefan
Instead of that use MR_inContext: on the object whose id is objectID. So something like this:
MyObject *myObject = [getMeAnObject];
[MagicalRecord saveWithBlock:^(NSManagedObjectContext *localContext) {
MyObject *myObjectLocal = [myObject MR_inContext:localContext];
}];
Related
I have an array which I want to add to a CoreData database, I have made a forEach to go through the array and then save the data in CoreData, the problem that only saves a value, below I write the code, There is a problem in the code?
class AquarisB: NSManagedObject, Identifiable {
#NSManaged public var nombre : String
}
struct Inici: View {
var body: some View {
var data : Array = [nombre: test1, nombre: test2]
var nuevoAcuari = Aquaris(context: self.contexto)
#Environment(\.managedObjectContext) var contexto
data.forEach { (temp) in
nuevoAcuari.nombre = temp.nombre
}
do {
try self.contexto.save()
} catch let error as NSError {
print("error al guardar", error.localizedDescription)
}
}
}
As I said in my comment, you need to create a new entity for each item in your data array. Something like this should be enough.
for nombre in data {
var nuevoAcuari = Aquaris(context: contexto)
nuevoAcuari.nombre = nombre
}
do {
try self.contexto.save()
} catch let error as NSError {
print("error al guardar", error.localizedDescription)
}
The managed object context acts as a scratch pad, each time you create an object on it, it is not saved until you call save on it explicitly. If you want to add multiple items then you need to create them and then call save.
In your code all you are doing is updating the object that you have created and then calling save on it. You need to create an object for each item that that you wish to save.
My managedObjectContext hierarchy is as follows: (PSC)<-(writerMOC -- private)<-(mainMOC -- main)<-(backgroundMOC -- private)
I have an NSManagedObject who "name" property is "Banana".
In the backgroundMOC, I get a reference to the object with backgroundMOC.objectWithID, change the NSManagedObject's "name" property to "Apple", and subsequently set it's "syncStatus" property to 1 (flagged for synchronization), then recursively save the moc's with the following routine:
func saveManagedContext(moc: NSManagedObjectContext, shouldSync: Bool = true, completion: (() -> Void)? = nil)
{
print("\nSaving managed object context...")
do {
try moc.save()
if let parentContext = moc.parentContext {
parentContext.performBlock {
self.saveManagedContext(parentContext, shouldSync: shouldSync, completion: completion)
}
}
else {
if shouldSync { SyncEngine.sharedInstance.synchronize(shouldPushUpdates: true) }
completion?()
}
print("Finished saving managed object context...")
} catch {
logger.error("\(error)")
}
}
Once the last moc is saved, a sync routine is called which does its work on the backgroundMOC, which queries the local store for all objects whose syncStatus is 1, again this fetch is called on the backgroundMOC.
let fetchRequest = NSFetchRequest(entityName: entity.name)
let syncPredicate = NSPredicate(format: "%K == %d", JSONKey.SyncStatus.rawValue, 1)
fetchRequest.predicate = syncPredicate
return try backgroundMOC.executeFetchRequest(fetchRequest) as? [SyncableManagedObject] ?? []
This correctly returns the updated object in the array, however, that object's syncStatus property equals 0, and its "name" property is still set to "Banana".
This is really causing me headaches, I felt like i had totally understood how managedObjectContext blocks should work, but this has proven to be quite a puzzle.
UPDATE
Here's the code that prompts the update. This is called from the main thread when the cell is tapped.
func updateNameForCell(cell: UITableViewCell)
{
///gets the object id from the fetchedResultsController
guard let fruitMetaID = tableController.objectIDForCell(cell) else { return }
let backgroundMOC = CoreDataController.sharedInstance.newBackgroundManagedObjectContext()
backgroundMOC.performBlock {
do {
guard let fruit = (backgroundMOC.objectWithID(fruitMetaID) as? FruitMetaData)?.fruit else {
throw //Error
}
print(fruit.name) // "Banana"
fruit.name = "Apple"
fruit.needsSynchronization() //Sets syncStatus to 1
CoreDataController.sharedInstance.saveManagedContext(backgroundMOC)
}
catch {
//handle error
}
}
}
UPDATE AGAIN
Maybe I'm not creating the contexts right. Enlighten me please!
/// The parent to all other NSManagedObjectContexts. Responsible for writting to the store.
lazy var writerManagedObjectContext: NSManagedObjectContext =
{
let managedObjectContext = NSManagedObjectContext(concurrencyType: .PrivateQueueConcurrencyType)
managedObjectContext.performBlockAndWait {
managedObjectContext.persistentStoreCoordinator = self.persistentStoreCoordinator
}
return managedObjectContext
}()
lazy var mainManagedObjectContext: NSManagedObjectContext =
{
let managedObjectContext = NSManagedObjectContext(concurrencyType: .MainQueueConcurrencyType)
managedObjectContext.performBlockAndWait {
managedObjectContext.parentContext = self.writerManagedObjectContext
}
return managedObjectContext
}()
/// The context associated with background syncing..
func newBackgroundManagedObjectContext() -> NSManagedObjectContext
{
let backgroundManagedObjectContext = NSManagedObjectContext(concurrencyType: .PrivateQueueConcurrencyType)
backgroundManagedObjectContext.performBlockAndWait {
backgroundManagedObjectContext.parentContext = self.mainManagedObjectContext
}
return backgroundManagedObjectContext
}
Holding onto child MOCs (children of the main context) is fraught with issues. I would recommend creating a new child (aka backgroundMOC) for each operation that you do.
Without seeing all of your code this looks like an issue with the child context getting out of sync.
Update
Assuming that your creation of the backgroundMOC sets the mainMOC as its parent then I wonder about the -objectWithID: and what it is returning.
I also wonder about your -performBlock: calls. In my head the threading looks fine but better to test. Try changing to -performBlockAndWait: just to test and see if there is a threading race condition. Not a permanent change but eliminates that part of the code as a source of the issue.
Before fetchRequest is called, you should reset context.
backgroundMOC.reset() // add this line
let fetchRequest = NSFetchRequest(entityName: entity.name)
let syncPredicate = NSPredicate(format: "%K == %d", JSONKey.SyncStatus.rawValue, 1)
fetchRequest.predicate = syncPredicate
return try backgroundMOC.executeFetchRequest(fetchRequest) as? [SyncableManagedObject] ?? []
The reason is FruitMetaData is an object(or class) so changing one of its properties/Core Data attributes does not register as a change to the results array ... the object references in the array remain the same.
And NSFetchRequest still returns the same result(by using cache). When use context.reset().This tells the context in the extension to fetch new data every time and ignore the cache.
I've been chasing a bug for a while now and I can't figure it out. I have a class that takes a bunch of parsed data and then calls a method to create new core data "Article" object for each element created from the parsed data. I've shown how I declare the NSManagedObjectContext below.
You will also see the method
Article.createFLOArticleWithStructure(element, inManagedObjectContext: self.articleContext)
I placed this method in an extension to clean up the code. The method is show below.
import Foundation
class FLODataHandler : NSObject, FLOConnectionHandlerDelegate, FLOParserHandlerDelegate, TriathleteParserHandlerDelegate, VeloNewsParserHandlerDelegate, CyclingNewsParserHandlerDelegate, RoadBikeActionParserHandlerDelegate, IronmanParserHandlerDelegate
{
let appDelegate: AppDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
lazy var articleContext: NSManagedObjectContext = self.appDelegate.managedObjectContext!
func floParserHandlerDidFinishParsing(parserHandler : FLOParserHandler)
{
for element in self.floParserHandler!.XMLParsedDataArray!
{
// The pubDate, tilte and link and indicator have been added to the titleLinkArray. I will now add the data to a Core Data Entity
// in the Article+NewsFeedArticle class.
Article.createFLOArticleWithStructure(element, inManagedObjectContext: self.articleContext)
}
}
Extension Code
extension Article
{
class func createFLOArticleWithStructure(articleStructure: DateTitleLink, inManagedObjectContext context: NSManagedObjectContext) -> (Article)
{
// Core data is much simpler in Swift. I have not commented this code since I do not know if it's working yet.
var article = Article()
//var entity = NSEntityDescription("Article", inManagedObjectContext: context)
let fetchRequest = NSFetchRequest(entityName: "Article")
let predicate = NSPredicate(format: "feed == 'FLO Cycling' AND title == %#", articleStructure.title!)
let sortDescriptor = NSSortDescriptor(key: "pubDate", ascending: true)
fetchRequest.sortDescriptors = [sortDescriptor]
// Set up NSError
var fetchError : NSError?
// When you perform a fetch the returned object is an array of the Atricle Entities.
let fetchedObjects = context.executeFetchRequest(fetchRequest, error: &fetchError) as! [Article]
if fetchedObjects.count > 1
{
println("Error! in Article+NewFeedArticle.swift")
}
else if fetchedObjects.count == 0
{
article = NSEntityDescription.insertNewObjectForEntityForName("Article", inManagedObjectContext: context) as! Article
article.feed = "FLO Cycling"
article.pubDate = articleStructure.date!
article.title = articleStructure.title!
article.link = articleStructure.link!
article.theNewArticle = NSNumber(int: 1)
var error : NSError?
if(context.save(&error))
{
println(error!.localizedDescription)
}
}
else if fetchedObjects.count == 1
{
article = fetchedObjects[fetchedObjects.endIndex - 1]
}
return article
}
When I run the code I get stopped on the following line of the extension code and receive the following errors.
article = NSEntityDescription.insertNewObjectForEntityForName("Article", inManagedObjectContext: context) as! Article
CoreData: error: Failed to call designated initializer on
NSManagedObject class 'FLOCycling1_1_1.Article' CoreData: warning:
Unable to load class named 'Article' for entity 'Article'. Class not
found, using default NSManagedObject instead. Could not cast value of
type 'NSManagedObject_Article_' (0x7fe59c3515e0) to
'FLOCycling1_1_1.Article' (0x106139f70).
I've read online about using a prefix in the data model. I've added this to no avail. If you have any idea how I can fix this error I would appreciate the help.
ADDED****
Here is the Article.swift file on request.
import Foundation
import CoreData
#objc class Article: NSManagedObject
{
#NSManaged var feed: String
#NSManaged var link: String
#NSManaged var pubDate: NSDate
#NSManaged var theNewArticle: NSNumber
#NSManaged var title: String
}
Take care,
Jon
The issue had to do with my declaration of Article in this line here.
var article = Article()
In the Swift version calling the line of code above allocates and initializes memory for the Article. In the Objective-C version of my code I called the following.
Article *article = nil;
While I am not sure why, allocating and initializing the Article is the issue. I found this post here about a similar error.
Failed to call designated initializer on NSManagedObject class 'ClassName'
To fix this I changed the code to
var article = Article?()
To be clear, I also changed the Article class to ProjectName.Article.
I hope this helps someone else.
Take care,
Jon
While Strings appears to be fine I'm having some trouble storing Integers into Core Data. Following tutorials and reading available information out there doesn't seem to be helping me who has no Objective-C background. (Swift seemed like a straight forward language like the languages I'm fluent with PHP/OOPHP/JavaScript/VBScript/... thus I started playing with it and so far have been able to do everything I wanted, almost)
What I want to do now is, to receive the JSON data and store it into Core Data
Here's my Core Data
Entity name: Category
Its Attributes:
id Int16
title String
description String
My Swift model? file: Category.swift
import CoreData
class Category: NSManagedObject {
#NSManaged var id: Int //should I declare this as Int16?
#NSManaged var title: String
#NSManaged var description: String
}
I'm using SwiftyJASON extension? and NSURLSession protocol? to get the data and to parse it as follow:
import UIKit
import CoreData
class ViewController: UIViewController {
let managedObjectContext = (UIApplication.sharedApplication().delegate as AppDelegate).managedObjectContext
override func viewDidLoad() {
super.viewDidLoad()
fetchData()
}
func fetchData() {
var url = NSURL.URLWithString("http://domain.com/index.php?r=appsync/read&id=category")
var session = NSURLSession.sharedSession()
session.dataTaskWithURL(url, completionHandler: {(data, response, error) in
// parse data into json
let json = JSONValue(data)
let entityDescription = NSEntityDescription.entityForName("Category", inManagedObjectContext: self.managedObjectContext)
let category = Category(entity: entityDescription, insertIntoManagedObjectContext: self.managedObjectContext)
for item in json.array! {
category.id = item["id"].string!.toInt()! //goes KABOOM!
category.title = item["title"].string!
category.description = item["description"].string!
managedObjectContext?.save(nil)
}
dispatch_async(dispatch_get_main_queue()) {
// do something
}
}).resume()
}
}
Let's assume the JASON data is:
[{"id":"1","title":"cat1","description":"blabala one"},{"id":"2","title":"cat2","description":"blabala two"}]
At line where it says category.id = item["id"].string!.toInt()! xCode goes KABOOM, what am I doing wrong here?
Notes/More questions:
I tried changing id type within Core Data to Int32 and then declaring it as just Int
in the model (and not Int16 or Int32) which reduced some errors but
xCode still crashes
Probably the way I'm looping stuff is not the best way to do this,
what's the better way of storing array of data into core data at
once?
Most of the tutorials I've seen there's no id's for Entities(tables), am I missing something here?
References:
SiftyJSON: https://github.com/lingoer/SwiftyJSON
Core Data tutorial:
http://rshankar.com/coredata-tutoiral-in-swift-using-nsfetchedresultcontroller/
EDIT > Working code:
Category.swift model file which can be auto generated using File>New>File>iOS>Core Data>NSManagedObject subclass [swift, no need for bridging header but you need to manually add #objc line as below]
import CoreData
#objc(Category) //Wouldn't work without this
class Category: NSManagedObject {
#NSManaged var id: NSNumber //has to be NSNumber
#NSManaged var title: String
#NSManaged var mydescription: String //"description" is reserved so is "class"
}
ViewController.swift
import UIKit
import CoreData
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
fetchData()
}
func fetchData() {
var url = NSURL.URLWithString("http://domain.com/index.php?r=appsync/read&id=category")
var session = NSURLSession.sharedSession()
session.dataTaskWithURL(url, completionHandler: {(data, response, error) in
let json = JSONValue(data)
let managedObjectContext = (UIApplication.sharedApplication().delegate as AppDelegate).managedObjectContext //this line had to be moved here
let entityDescription = NSEntityDescription.entityForName("Category", inManagedObjectContext: managedObjectContext)
for item in json.array! {
let category = Category(entity: entityDescription, insertIntoManagedObjectContext: managedObjectContext) //this line has to be in inside for loop
category.id = item["id"].string!.toInt()!
category.title = item["title"].string!
category.mydescription = item["description"].string!
managedObjectContext?.save(nil)
}
dispatch_async(dispatch_get_main_queue()) {
// do something
}
}).resume()
}
}
Sample fetching data code:
func requestData() {
let appDel:AppDelegate = UIApplication.sharedApplication().delegate as AppDelegate
let context:NSManagedObjectContext = appDel.managedObjectContext!
var request = NSFetchRequest(entityName: "Category")
request.returnsObjectsAsFaults = false
var results:NSArray = context.executeFetchRequest(request, error: nil)
//println(results)
for category in results {
var cat = category as Category
println("\(cat.id),\(cat.title),\(cat.mydescription)")
}
}
P.S. Make sure to Clean your project and delete the app from simulator after changing Model
Scalar types (integers, floats, booleans) in core data are broken in the current Swift beta (5). Use NSNumber for the properties, and file a radar.
object.intProperty = NSNumber(int:Int(item["id"] as String))
(Typed on the phone, so sorry if that's wrong, and I know it's disgusting code - hence, file a radar!)
Or, in your specific case, looking at the JSON, use String. Those IDs are coming in as strings anyway.
Updated for Swift 2
If your JSON data is really of type [[String:String]], you can use the following code in order to set category.id:
if let unwrappedString = item["id"], unwrappedInt = Int(unwrappedString) {
category.id = unwrappedInt
}
Does anyone has sample code for ordering in UITableView using NSOrderedSet?
Had read many articles about reordering, but still don't understand how to do this in iOS5.
Hi i implemented it like this. The "currentObject" is root object of the relationship and "subItems" the name of the ordered relationship in the model which is managed by the UITableViewController.
- (void)moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath
{
NSMutableOrderedSet* orderedSet = [self.currentObject mutableOrderedSetValueForKey:#"subItems"];
NSInteger fromIndex = fromIndexPath.row;
NSInteger toIndex = toIndexPath.row;
// see http://www.wannabegeek.com/?p=74
NSIndexSet *indexes = [NSIndexSet indexSetWithIndex:fromIndex];
if (fromIndex > toIndex) {
// we're moving up
[orderedSet moveObjectsAtIndexes:indexes toIndex:toIndex];
} else {
// we're moving down
[orderedSet moveObjectsAtIndexes:indexes toIndex:toIndex-[indexes count]];
}
[self.dataStore saveObjectContext];
}