Core data entity manager - ios

Question

I want to write class for manage all entity that i have in my application.
there is my code fore managerClass for one custom entity, but I have a problem to set manageObject type in this context.
public func clearEntityContex() {
let fetchRequest: NSFetchRequest<Shop> = Shop.fetchRequest()
if let fetchResult = try? self.stack.mainQueueContext.fetch(fetchRequest){
for user : Shop in fetchResult {
self.stack.mainQueueContext.delete(user as Shop)
}
do {
try stack.mainQueueContext.save()
}
catch {
debugPrint(error.localizedDescription)
}
}
}
//MARK: _fetch Contex
public func fetchsShopEntity() -> [Shop]? {
var shops : [Shop]?
let fetchRequest: NSFetchRequest<Shop> = Shop.fetchRequest()
do {
let fetchResult =
try self.stack.mainQueueContext.fetch(fetchRequest)
if fetchResult.count > 0 {
shops = fetchResult
}
}
catch {
fatalError("Failed to fetch Account: \(error)")
}
return shops
}
//MARK: _save entity
public func saveEntityInModel(entityItem : Shop){
if let entity = NSEntityDescription.entity(forEntityName: "Shop", in: self.stack.mainQueueContext) {
if let contex = NSManagedObject(entity: entity, insertInto: self.stack.mainQueueContext) as? Shop {
contex.packID = entityItem.packID
contex.packName = entityItem.packName
contex.packImage = entityItem.packImage
contex.priceDolar = entityItem.priceDolar
contex.packDescription = entityItem.packDescription
do {
try stack.mainQueueContext.save()
}
catch {
debugPrint(error.localizedDescription)
}
}
}
}
for example i want to write method that can clear any entityContext. but i cant pass manageObject to this method.
public func clearEntityContex(entityObject: NSManagedObject) {
let fetchRequest: NSFetchRequest<NSFetchRequestResult> = entityObject.fetchRequest()
if let fetchResult = try? self.stack.mainQueueContext.fetch(fetchRequest){
for entity in fetchResult {
self.stack.mainQueueContext.delete(entity as entityObject)
}
do {
try stack.mainQueueContext.save()
}
catch {
debugPrint(error.localizedDescription)
}
}
}
how can solve pass NSManagedObject to this method?
thanks for all reply

Answer 1

Here's a more generic implementation that we use in our projects.
import CoreData
class ACSwiftCoreData: ACCoreDataPlugin {
let managedObjectModelName: String
let databasePath: URL
init(managedObjectModelName: String, databasePath: URL) {
self.managedObjectModelName = managedObjectModelName
self.databasePath = databasePath
}
// MARK: Managed Object Contexts
private var sharedContext: NSManagedObjectContext?
func getSharedManagedObjectContext() throws -> NSManagedObjectContext {
if let sharedContext = self.sharedContext {
return sharedContext
}
let context = try self.createManagedObjectContext()
self.sharedContext = context
return context
}
func createManagedObjectContext() throws -> NSManagedObjectContext {
let storeCoordinator = try self.getPersistentStoreCoordinator()
let managedObjectContext = NSManagedObjectContext(concurrencyType: .mainQueueConcurrencyType)
managedObjectContext.persistentStoreCoordinator = storeCoordinator
managedObjectContext.mergePolicy = NSMergePolicy(merge: NSMergePolicyType.mergeByPropertyObjectTrumpMergePolicyType)
return managedObjectContext
}
// MARK: Creating Entities
func createEntityInSharedContext<EntityType>(_ entityName: String) throws -> EntityType {
let context = try self.getSharedManagedObjectContext()
return try self.createEntity(entityName, context: context)
}
func createEntity<EntityType>(_ entityName: String, context: NSManagedObjectContext) throws -> EntityType {
let entity = NSEntityDescription.insertNewObject(forEntityName: entityName, into: context)
guard let expectedEntity = entity as? EntityType else {
throw self.errorWithMessage("ACSwiftCoreData: Entity for name \(entityName) does not match class \(EntityType.self).")
}
return expectedEntity
}
// MARK: Saving Entity
func saveEntity(_ entity: NSManagedObject) throws {
guard let context = entity.managedObjectContext else {
throw errorWithMessage("ACSwiftCoreData: Cannot save Entity. ManagedObjectContext is missing.")
}
if context.hasChanges {
try context.save()
}
}
// MARK: Delete Entity
func deleteEntity(_ entity: NSManagedObject) throws {
guard let context = entity.managedObjectContext else {
throw errorWithMessage("ACSwiftCoreData: Cannot delete Entity. ManagedObjectContext is missing.")
}
context.delete(entity)
try context.save()
}
// MARK: Fetch Requests
func fetchEntitiesInSharedContext<EntityType: AnyObject>(_ entityName: String, predicate: NSPredicate?) -> [EntityType] {
guard let context = try? self.getSharedManagedObjectContext() else {
return [EntityType]()
}
return self .fetchEntities(entityName, context: context, predicate: predicate)
}
func fetchEntities<EntityType: AnyObject>(_ entityName: String, context: NSManagedObjectContext, predicate: NSPredicate?) -> [EntityType] {
let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: entityName)
fetchRequest.predicate = predicate
let results = try? context.fetch(fetchRequest)
guard let resultEntitys = results as? [EntityType] else {
return [EntityType]()
}
return resultEntitys
}
// MARK: Technical Details
private var storeCoordinator: NSPersistentStoreCoordinator?
private func getPersistentStoreCoordinator() throws -> NSPersistentStoreCoordinator {
if let storeCoordinator = self.storeCoordinator {
return storeCoordinator
}
let model = try self.getManagedObjectModel()
let storeCoordinator = NSPersistentStoreCoordinator(managedObjectModel: model)
var options = [AnyHashable: Any]()
options[NSMigratePersistentStoresAutomaticallyOption] = true
options[NSInferMappingModelAutomaticallyOption] = true
try storeCoordinator.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: self.databasePath, options: options)
self.storeCoordinator = storeCoordinator
return storeCoordinator
}
private var objectModel: NSManagedObjectModel?
private func getManagedObjectModel() throws -> NSManagedObjectModel {
if let objectModel = self.objectModel {
return objectModel
}
let momName = self.managedObjectModelName
guard let modelUrl = Bundle.main.url(forResource: momName, withExtension:"momd") else {
throw self.errorWithMessage("ACSwiftCoreData: DataModel Url could not be created.")
}
guard let objectModel = NSManagedObjectModel(contentsOf: modelUrl) else {
throw self.errorWithMessage("ACSwiftCoreData: DataModel could not be loaded.")
}
self.objectModel = objectModel
return objectModel
}
// MARK: Error handling
private func errorWithMessage(_ message: String) -> NSError {
let userInfo = [NSLocalizedDescriptionKey: message]
let error = NSError(domain: "com.appcron.accomponents", code: 0, userInfo: userInfo)
return error
}
}

Answer 2

In some project that I made and when I used CoreData, I usually create a Singleton with function to fetch, save and delete a CoreData object.
This is my CoreDataController:
import Foundation
import CoreData
import UIKit
final class CoreDataController {
static let sharedInstances = CoreDataController()
private var context: NSManagedObjectContext
private init(){
let application = UIApplication.shared.delegate as! AppDelegate
self.context = application.persistentContainer.viewContext
}
func loadAll() {
print("Fetch from CoreData")
let fetchRequest: NSFetchRequest<YourEntity> = YourEntity.fetchRequest()
do {
let entityArray = try self.context.fetch(fetchRequest)
guard entityArray.count > 0 else {
print("There aren't element in CoreData "); return}
} catch let error {
print("FetchRequest error")
print(" Print error: \n \(error) \n")
}
}
func save(entityToSave: String, item: String){
let entity = NSEntityDescription.entity(forEntityName: entityToSave, in: self.context)
let newItem = YourEntity(entity: entity!, insertInto: self.context)
newItem.name = item
do {
try self.context.save()
} catch let error {
print("Problem with \(newItem)")
print(" Print error: \n \(error) \n")
}
print("Element \(newItem) saved in CoreData")
}
func loadFromName(entityName:String, name: String) -> Any {
let request = NSFetchRequest<NSFetchRequestResult>(entityName: entityName)
request.returnsObjectsAsFaults = false
let predicate = NSPredicate(format: "yourEntityAttribute = %#", yourEntityAttribute)
request.predicate = predicate
let items = self.loadFromFetchRequest(request: request)
return items[0]
}
private func loadFromFetchRequest(request: NSFetchRequest<NSFetchRequestResult>) -> [Any] {
var array = [Any]()
do {
array = try self.context.fetch(request)
guard array.count > 0 else {print("There aren't element in CoreData"); return []}
for item in array {
print("Item: \(item)")
}
} catch let error {
print("FetchRequest Error")
print(" Print Error: \n \(error) \n")
}
return array
}
func delete(entityName: String, name: String) {
let item = self.loadFromName(entityName: entityName, name: name)
self.context.delete(item as! NSManagedObject)
do {
try self.context.save()
} catch let error {
print("Deleting problem")
print("Print Error: \n \(error) \n")
}
}
func loadData(entity: String) -> [YourEntity] {
let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: entity)
fetchRequest.returnsObjectsAsFaults = false
var data = [YourEntity]()
do {
data = try self.context.fetch(fetchRequest) as! [YourEntity]
} catch let error {
print("Print Error: \n \(error) \n")
}
return data
}
}
When you have to call, just write:
CoreDataController.sharedInstances.save(entityToSave: "Profile", item: textfield.text!)
or other functions!!!
I hope this is useful for you.
For use this Class with every Entity you can write like that:
let entity = NSEntityDescription.entity(forEntityName: entityToSave, in: self.context)
let newItem: Any
switch entityToSave {
case "YourEntity":
newItem = YourEntity(entity: entity!, insertInto: self.context)
(newItem as! YourEntity).entityAttribute = firstItem
(newItem as! YourEntity).entityAttribute = secondItem
case "YourEntity2":
newItem = YourEntity2(entity: entity!, insertInto: self.context)
(newItem as! YourEntity2).entityAttribute = firstItem
(newItem as! YourEntity2).entityAttribute = secondItem
case "YourEntity3":
newItem = YourEntity3(entity: entity!, insertInto: self.context)
(newItem as! YourEntity3).entityAttribute = firstItem
(newItem as! YourEntity3).entityAttribute = secondItem
case "YourEntity4":
newItem = YourEntity4(entity: entity!, insertInto: self.context)
(newItem as! YourEntity4).entityAttribute = firstItem
(newItem as! YourEntity4).entityAttribute = secondItem
default:
fatalError("Error in entityToSave function")
}
do {
try self.context.save()
} catch let error {
print("Problem to save \(newItem)")
print("Print Error: \n \(error) \n")
}
print("Element \(newItem) saved correctly")
}