how to save values in core data in swift - swift

Question

I have to apply checkmarks on the contacts received by using address book. When I'm selecting contacts then checkmarks appears but after scrolling it disappears. Secondly, I have to save these selected contacts into core data. Just have a look at that and tell me what I'm doing wrong.What Wrong i'am doing with Core Data.

Answer 1

class LogItem: NSManagedObject {
#NSManaged var section: String
#NSManaged var keys: String
}
Now declare the object of this class like this:
let newItem = NSEntityDescription.insertNewObjectForEntityForName("LogItem", inManagedObjectContext: self.managedObjectContext!) as! LogItem
newItem.section = "section Title"
newItem.keys = "keys text"
}
You can fetch the data as follows:
// request using the LogItem entity
let fetchRequest = NSFetchRequest(entityName: "LogItem")
// Execute the fetch request, and cast the results to an array of LogItem objects
if let fetchResults = managedObjectContext!.executeFetchRequest(fetchRequest, error: nil) as? [LogItem] {
println(fetchResults[0].section) // prints "section title"
println(fetchResults[0].key) // prints key text
}
Please Make sure that core data is able to save only properties.
According to apple documentation, “The Core Data framework provides
generalized and automated solutions to common tasks associated with
object life-cycle and object graph management, including persistence.”

Answer 2

First, you add CoreData, then go to AppDelegate and you will see this code:
lazy var persistentContainer: NSPersistentContainer = {
let container = NSPersistentContainer(name: "Model_data")
container.loadPersistentStores(completionHandler: { (storeDescription, error) in
if let error = error as NSError? {
fatalError("Unresolved error \(error), \(error.userInfo)")
}
})
return container
}()
In: let container . . . you see (name: "Model_data")
This name needs to be same as your model file name.
Then go to your View Controller and add:
let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
let newItem = Item(context: self.context)
Item is an entity from your model object.
add newItem to an array like:
self.itemArray.append(newItem)
Then, add next logic:
fileprivate func saveContext() {
do {
try context.save()
// if it is table view, you need to reload here. tableView.reloadData()
} catch {
print("Failed to with error: \(error)")
}
}
if loading is problem add this logic:
fileprivate func loadContext() {
let request: NSFetchRequest<Item> = Item.fetchRequest()
do {
itemModel = try context.fetch(request)
} catch {
print("Error in request: \(error)")
}
}
Save and load.