UserDefaults for NSMutableAttributedString

Question

I have a textView which is the whole screen of the app. The users input new text, change the properties etc. I want the app save textview content with its properties for next times. I came up with userDefaults. I tried much but nothing happens. I couldn't find a solution to this. I tried this solution from stackoverflow https://stackoverflow.com/a/36940864/12698480 but no change. Again empty screen comes on the textview. My code as an extension to Userdefaults is as below:

//Save text
func setNSMutableText(string: NSMutableAttributedString?, forKey key: String){
        var stringData: NSData?
        if let string = string {
            do {
                stringData = try NSKeyedArchiver.archivedData(withRootObject: string, requiringSecureCoding: false) as NSData?
                set(stringData, forKey: key)
                print("archived NSMutableData")
            } catch let err {
                print("error archiving string data", err)
            }
        }
    }

//LOAD text
    func getNSMutableForKey(key: String) -> NSMutableAttributedString? {
        var string: NSMutableAttributedString?
        if let stringData = data(forKey: "screentextKey") {
            do {
                string = try NSKeyedUnarchiver.unarchivedObject(ofClass: NSMutableAttributedString.self, from: stringData)
                print("UNARchived string data!!!")
            } catch let err {
                print("error extracting string data", err)
            }
        }
        return string
    }

Usage:

//For saving
UserDefaults.standard.setNSMutableText(string: NSMutableAttributedString(attributedString: myTextView.attributedText), forKey: "screentextKey")

//For loading
override func viewDidLoad() {
   super.viewDidLoad()

   let oldstring = (UserDefaults.standard.getNSMutableForKey(key: "screentextKey"))!
   myTextView.attributedText = oldstring
}

What is the problem? I saw that someone's suggestion about using NSAttributedString at the place of NSMutableAttributedString. I tried that way also, but no change.

Answer 1

In order to make it work the way you want, you don't have to use NSKeyedArchiver.archivedData. Instead it is much better to use CoreData to save the data in device memory(Because if I got the idea it is not the big amount of data), Structure it using XCDataModel and then, fetch it using NSFetchController.

in XCDataModel you have to create ENTITY and set attributes for it(String, Bool, Double etc.)

After that you will have to set NSFetchedResultsController in order to manage the process.

Here is the way I would set it :

1. Import CoreData

2. set persistent container(Container for your data):

   static let persistentContainer: NSPersistentContainer = { let container = NSPersistentContainer(name: "RebelFitness") container.loadPersistentStores { (_, error) in if let error = error as NSError? { fatalError("Unresolved error (error), (error.userInfo)") } } return container }()

3. set NSFetchedResultsController:

   lazy var fetchedResultsController: NSFetchedResultsController = {

        let fetchRequest: NSFetchRequest< YourEntityName > = YourEntityName.fetchRequest()
        fetchRequest.sortDescriptors = [NSSortDescriptor(key: "distance", ascending: true), NSSortDescriptor(key: "duration", ascending: true)] //Here you use descriptor to sort the data in my example distance comes in array first and then any other elements
        let fetchedResultsController = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: CoreDataStack.persistentContainer.viewContext, sectionNameKeyPath: nil, cacheName: nil)
        fetchedResultsController.delegate = self as? NSFetchedResultsControllerDelegate
   
        return fetchedResultsController
   
    }()
   

4. Function used to fetch the saved data:

static var context: NSManagedObjectContext { return persistentContainer.viewContext }

In this function we are fetching data to new array which will pass it to your array which supplies the UIKit elements with data

func loadIsCurrent() -> [YourEntityName] {
        
        var _data : [YourEntityName] = []
        let context = persistentContainer.viewContext
        let fetchRequest: NSFetchRequest< YourEntityName > = YourEntityName.fetchRequest()
        fetchRequest.sortDescriptors = [NSSortDescriptor(key: "distance", ascending: false), NSSortDescriptor(key: "duration", ascending: true)]
        
        do {
            let data = try context.fetch(fetchRequest)
            if(sessions.count > 0) {
                _data = data
            }
        } catch {
            print("Something happened while trying to retrieve tasks...")
        }
        return _data
    }

5. saving the data to coreData:

func saveContext () { let context = persistentContainer.viewContext

guard context.hasChanges else {
  return
}
    
do {
  try context.save()
    try fetchedResultsController.performFetch()
} catch {
  let nserror = error as NSError
  fatalError("Unresolved error \(nserror), \(nserror.userInfo)")
    }

}