How to get values just created from NSManagedObject - ios

Question

I have these classes:
import Foundation
import CoreData
public class Friend: NSManagedObject {
}
and
import Foundation
import CoreData
extension Friend {
#nonobjc public class func fetchRequest() -> NSFetchRequest<Friend> {
return NSFetchRequest<Friend>(entityName: "Friend")
}
#NSManaged public var profileImageName: String?
#NSManaged public var name: String?
#NSManaged public var messages: NSSet?
}
// MARK: Generated accessors for messages
extension Friend {
#objc(addMessagesObject:)
#NSManaged public func addToMessages(_ value: Message)
#objc(removeMessagesObject:)
#NSManaged public func removeFromMessages(_ value: Message)
#objc(addMessages:)
#NSManaged public func addToMessages(_ values: NSSet)
#objc(removeMessages:)
#NSManaged public func removeFromMessages(_ values: NSSet)
}
and
import UIKit
import CoreData
extension FriendsController {
func setupData(){
let context = AppDelegate().context
let mark = Friend(context: context)
mark.name = "mark"
mark.profileImageName = "zuck"
let message1 = Message(context: context)
message1.text = "Hello, my name is mark, nice to meet you"
message1.date = Date()
message1.friend = mark
let steve = Friend(context: context)
steve.name = "steve"
steve.profileImageName = "steve"
let message2 = Message(context: context)
message2.text = "Hello, my name is steve"
message2.date = Date()
message2.friend = steve
messages = [message1, message2]
}
}
and later, I'm trying to access 'message?.friend?.name', but it's always nil...
class MessageCell: BaseCell {
var message: Message? {
didSet {
nameLabel.text = message?.friend?.name
if let profileImageName = message?.friend?.profileImageName {
profileImageView.image = UIImage(named: profileImageName)
}
messageLabel.text = message?.text
if let date = message?.date {
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "h:m a"
timeLabel.text = dateFormatter.string(from: date)
}
}
}
}
Should I do something else with the context to load these managed objects?
Doesn't make much sense, since I've just create them, just passing as reference to a different class, they should be available.

Answer 1

I think the problem is here:
let context = AppDelegate().context
This creates a new instance of the AppDelegate, it doesn't reference the existing instance. Since that new instance is created in the setupData method, it is deallocated when that method completes. And because you haven't saved, the data isn't persisted before the method completes. So the messages array contains NSManagedObjects which no longer have a reference to a valid context, and their values are therefore nil.
You should probably access the existing AppDelegate instance using:
let appDelegate = UIApplication.shared.delegate as! AppDelegate
let context = appDelegate.context