CoreData - toant-dev/toandev.github.io GitHub Wiki

.xcdatamodeld: Manage entities, attributes...

Can use codegen to create models

• Extension to manage data

extension NSManagedObject {
    class var context: NSManagedObjectContext! {
        let appDelegate = UIApplication.shared.delegate as! AppDelegate
        return appDelegate.persistentContainer.viewContext
    }

    class var request: NSFetchRequest<NSManagedObject> {
        return NSFetchRequest(entityName: String(describing: self))
    }

    func save(success: (() -> Void)?, fail: ((Error) -> Void)?) {
        guard let context = self.managedObjectContext else {
            fail?(NSError(domain: "", code: 1, userInfo: nil))
            return
        }
        if context.hasChanges {
            do {
                try context.save()
                success?()
            } catch {
                fail?(error)
            }
        } else {
            let error = NSError(domain: "Data not change", code: 0, userInfo: nil)
            fail?(error)
        }
    }

    func delete(completed: ((Error?) -> Void)?) {
        self.managedObjectContext?.delete(self)
        self.save(success: {
            completed?(nil)
        }) { (error) in
            completed?(error)
        }
    }

    class func all(predicate: NSPredicate?, success: (([NSManagedObject]) -> Void)?, fail: ((Error) -> Void)?) {
        request.predicate = predicate
        do {
            let result = try context.fetch(request)
            success?(result)
        } catch {
            fail?(error)
        }
    }

    class func findByObjectId(objectId: NSManagedObjectID) -> NSManagedObject? {
        do {
            return try self.context.existingObject(with: objectId)
        } catch {
            return nil
        }
    }

    class func findBy(predicate: NSPredicate?, success: ((NSManagedObject?) -> Void)?, fail: ((Error) -> Void)?) {
        request.predicate = predicate
        do {
            let result = try context.fetch(request)
            success?(result.first)
        } catch {
            fail?(error)
        }
    }
}

• Example

class ViewController: UIViewController {

    var appDelegate: AppDelegate!
    var context: NSManagedObjectContext!

    override func viewDidLoad() {
        super.viewDidLoad()
        appDelegate = UIApplication.shared.delegate as! AppDelegate
        context = appDelegate.persistentContainer.viewContext
    }

    func createNewUser() {
        let user = Users(context: context)
        user.update(username: "createNewUser", password: "passwor_3", name: "createNewUser", age: 3)
        user.save(success: {
            print("Create user success")
        }) { (err) in
            print("Create user fail: \(err.localizedDescription)")
        }
    }

    func updateUser() {
        let predicate = NSPredicate(format: "name like %@", "createNewUser")
        Users.findBy(predicate: predicate, success: { user in
            guard let user = user as? Users else { return }

            user.update(username: "update username", password: "update password", name: "update name", age: 100)
            user.save(success: {
                print("Update success")
            }, fail: { (err) in
                print("Fetch fail cmnr: \(err)")
            })
        }) { (err) in
            print("Fetch fail cmnr: \(err)")
        }
    }
}