Brtdku

There is an option in my app to add new excercises (via user input), i've managed to set the alert and add feature, but I can't save the data added and let it be persistent after closure and that.

//

//  ExcerciseListViewController.swift

//  OneRepMax

//

//  Created by Mauro Garcia on 17/01/2019.

//  Copyright © 2019 Mauro Garcia. All rights reserved.

//



import Foundation

import UIKit

import CoreData





class ExcerciseListViewController: UIViewController, UITableViewDelegate {



override func viewDidLoad() {

    super.viewDidLoad()



    title = "Excercises"

    tableView.register(UITableViewCell.self, forCellReuseIdentifier: "Cell")



// This view controller itself will provide the delegate methods and row data for the table view.



    tableView.delegate = self

    tableView.dataSource = self





}





@IBOutlet weak var tableView: UITableView!







// Add a new excercise



@IBAction func addExcercise(_ sender: UIBarButtonItem) {



    let alert = UIAlertController(title: "New Excercise", message: "Add a new excercise", preferredStyle: .alert)



    let saveAction = UIAlertAction(title: "Save", style: .default) { [unowned self] action in



        guard let textField = alert.textFields?.first,

            let nameToSave = textField.text

            else {

              return

        }

        print(nameToSave)



        self.excercises.append(nameToSave)

        self.tableView.reloadData()

    }



    let cancelAction = UIAlertAction(title: "Cancel", style: .cancel)

    alert.addTextField()

    alert.addAction(saveAction)

    alert.addAction(cancelAction)



    present(alert, animated: true)

}





var excercises: [String] = 











}



// MARK: - UITableViewDataSource



extension ExcerciseListViewController: UITableViewDataSource {



func tableView(_ tableView: UITableView,

               numberOfRowsInSection section: Int) -> Int {

    print(excercises.count)



    return excercises.count

}



func tableView(_ tableView: UITableView,

               cellForRowAt indexPath: IndexPath)

    -> UITableViewCell {



        let cell =

            tableView.dequeueReusableCell(withIdentifier: "Cell",

                                          for: indexPath)

        cell.textLabel?.text = excercises[indexPath.row]

        return cell

}



// What happens when user touch an excercise



func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {

let excerciseChosen = "(excercises[indexPath.row])"

goBackToOneButtonTapped((Any).self)

excUserChose = excerciseChosen

print(excUserChose)

print("You tapped cell number (indexPath.row).")

print(excerciseChosen)



NotificationCenter.default.post(name: NSNotification.Name(rawValue: "changeText"), object: nil)

}



func goBackToOneButtonTapped(_ sender: Any) {

    performSegue(withIdentifier: "unwindToViewController", sender: self)



}











}





// TODO: save user input

In my AppDelegate.swift

// MARK: - Core Data stack



lazy var persistentContainer: NSPersistentContainer = {

    /*

     The persistent container for the application. This implementation

     creates and returns a container, having loaded the store for the

     application to it. This property is optional since there are legitimate

     error conditions that could cause the creation of the store to fail.

     */

    let container = NSPersistentContainer(name: "OneRepMax")

    container.loadPersistentStores(completionHandler: { (storeDescription, error) in

        if let error = error as NSError? {

            // Replace this implementation with code to handle the error appropriately.

            // fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.



            /*

             Typical reasons for an error here include:

             * The parent directory does not exist, cannot be created, or disallows writing.

             * The persistent store is not accessible, due to permissions or data protection when the device is locked.

             * The device is out of space.

             * The store could not be migrated to the current model version.

             Check the error message to determine what the actual problem was.

             */

            fatalError("Unresolved error (error), (error.userInfo)")

        }

    })

    return container

}()



// MARK: - Core Data Saving support



func saveContext () {

    let context = persistentContainer.viewContext

    if context.hasChanges {

        do {

            try context.save()

        } catch {

            // Replace this implementation with code to handle the error appropriately.

            // fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.

            let nserror = error as NSError

            fatalError("Unresolved error (nserror), (nserror.userInfo)")

        }

    }

}

I want to -when the user press "Save"- to save the data to be accesible after.
I've tried to implement CoreData but I have failed trying. Don't know what I'm doing wrong.

EDIT:

Code for adding and saving input

var excercisess: [NSManagedObject] = 





@IBAction func addExcercise(_ sender: UIBarButtonItem) {



    let alert = UIAlertController(title: "New Excercise", message: "Add a new excercise", preferredStyle: .alert)



    let saveAction = UIAlertAction(title: "Save", style: .default) { [unowned self] action in



        guard let textField = alert.textFields?.first,

            let nameToSave = textField.text

            else {

              return

        }



        self.save(name: nameToSave)

        self.tableView.reloadData()

    }



    let cancelAction = UIAlertAction(title: "Cancel", style: .cancel)

    alert.addTextField()

    alert.addAction(saveAction)

    alert.addAction(cancelAction)



    present(alert, animated: true)

}





func save(name: String) {

    guard let appDelegate = UIApplication.shared.delegate as? AppDelegate else {

        return

    }





    /*1.

     Before you can save or retrieve anything from your Core Data store, you first need to get your hands on an NSManagedObjectContext. You can consider a managed object context as an in-memory “scratchpad” for working with managed objects.

     Think of saving a new managed object to Core Data as a two-step process: first, you insert a new managed object into a managed object context; then, after you’re happy with your shiny new managed object, you “commit” the changes in your managed object context to save it to disk.

     Xcode has already generated a managed object context as part of the new project’s template. Remember, this only happens if you check the Use Core Data checkbox at the beginning. This default managed object context lives as a property of the NSPersistentContainer in the application delegate. To access it, you first get a reference to the app delegate.

     */

    let managedContext = appDelegate.persistentContainer.viewContext



    /*

     An NSEntityDescription object is associated with a specific class instance

     Class

     NSEntityDescription

     A description of an entity in Core Data.



     Retrieving an Entity with a Given Name here person

     */

    let entity = NSEntityDescription.entity(forEntityName: "Excercise", in: managedContext)!





    /*

     Initializes a managed object and inserts it into the specified managed object context.



     init(entity: NSEntityDescription,

     insertInto context: NSManagedObjectContext?)

     */

    let excercises = NSManagedObject(entity: entity, insertInto: managedContext)





    //we can simply create person object this way also.

   // let excercise = Excercise(context: managedContext)



    /*

     With an NSManagedObject in hand, you set the name attribute using key-value coding. You must spell the KVC key (name in this case) exactly as it appears in your Data Model

     */

    excercises.setValue(name, forKeyPath: "name")

    /*

     You commit your changes to person and save to disk by calling save on the managed object context. Note save can throw an error, which is why you call it using the try keyword within a do-catch block. Finally, insert the new managed object into the people array so it shows up when the table view reloads.

     */

    do {

        try managedContext.save()

        excercisess.append(excercises)

        tableView.reloadData()

        print("SAVED")

    } catch let error as NSError {

        print("Could not save. (error), (error.userInfo)")

    }

}

And the code for fetching:

func fetchAllExcercises(){

    guard let appDelegate = UIApplication.shared.delegate as? AppDelegate else {

        return

    }

    /*Before you can do anything with Core Data, you need a managed object context. */

    let managedContext = appDelegate.persistentContainer.viewContext



    /*As the name suggests, NSFetchRequest is the class responsible for fetching from Core Data.



     Initializing a fetch request with init(entityName:), fetches all objects of a particular entity. This is what you do here to fetch all Person entities.

     */

    let fetchRequest = NSFetchRequest<NSManagedObject>(entityName: "Excercise")



    /*You hand the fetch request over to the managed object context to do the heavy lifting. fetch(_:) returns an array of managed objects meeting the criteria specified by the fetch request.*/

    do {

        excercisess = try managedContext.fetch(fetchRequest)

    } catch let error as NSError {

        print("Could not fetch. (error), (error.userInfo)")

    }



}

There are several things that you still need once you have the xcdatamodeld file set up.
Your array should be an array of your CoreData entity.
var exercises = [Exercise]()
You need to create an instance of the managed object context.

let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext

Then you will need to use that instance to create new objects in the array, save the new objects and fetch them. Have a go at finding out how to create those functions (Youtube, web articles) and then see if you still have questions.