CRUD Operation with CoreData

Khushboo Gupta

29 October 2021

Hi guys, Today we will learn about how to implement CRUD Operation with CoreData in an ios application.

Before starting to code first we need to know what is CRUD Operation with CoreData –

Core Data is an object graph and persistence framework provided by Apple in the iOS and macOS operating system. It allows data organized by the relation entity-attribute model to be serialized into XML, binary, or SQLite stores.

Data Create –

create the context from persistent container
create an entity with a user
set value for the records for each key

Example –

let managedContext =
            appDelegate!.persistentContainer.viewContext
        
        // 2
        let entity =
            NSEntityDescription.entity(forEntityName: "Person",
                                       in: managedContext)!
        
        let person = NSManagedObject(entity: entity,
                                     insertInto: managedContext)
        
        // 3
        person.setValue(name, forKeyPath: "name")
      
        // 4
        do {
            try managedContext.save()
            people.append(person)
        } catch let error as NSError {
            print("Could not save. \(error), \(error.userInfo)")
        }

let managedContext =

appDelegate!.persistentContainer.viewContext

// 2

let entity =

NSEntityDescription.entity(forEntityName: "Person",

in: managedContext)!

let person = NSManagedObject(entity: entity,

insertInto: managedContext)

// 3

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

// 4

do {

try managedContext.save()

people.append(person)

} catch let error as NSError {

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

}

Update Data in Coredata-

prepare the request with a predicate for the entity.
Fetch record and set new value with key
save context

Example –

let managedContext =
            appDelegate!.persistentContainer.viewContext
        let fetchRequest:NSFetchRequest<NSFetchRequestResult> = NSFetchRequest.init(entityName: "PersonDetails")
        
        fetchRequest.predicate = NSPredicate(format: "name = %@", cellName)
        
        do
        {
            let value = try  managedContext.fetch(fetchRequest)
            
            let valueUpdate = value[index] as! NSManagedObject
            
            valueUpdate.setValue(name, forKeyPath: "name")
           
            do{
                try managedContext.save()
            }
            catch{
                print(error)
            }
        }catch{
            print(error)
        }

let managedContext =

appDelegate!.persistentContainer.viewContext

let fetchRequest:NSFetchRequest<NSFetchRequestResult> = NSFetchRequest.init(entityName: "PersonDetails")

fetchRequest.predicate = NSPredicate(format: "name = %@", cellName)

{

let value = try managedContext.fetch(fetchRequest)

let valueUpdate = value[index] as! NSManagedObject

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

do{

try managedContext.save()

}

catch{

print(error)

}

}catch{

print(error)

}

Delete Data in CoreData-

Prepare the request with a predicate for the entity
Fetch record and which we want to delete
make context.delete call

Example –

let managedContext =
                appDelegate!.persistentContainer.viewContext
            
            managedContext.delete(people[indexPath.row])
            
            
            do {
                try  managedContext.save()
                
                people.remove(at: indexPath.row)
                
                tableViewOutlet.deleteRows(at: [indexPath], with: .fade)
            } catch {
                let saveError = error as NSError
                print(saveError)
            }

let managedContext =

appDelegate!.persistentContainer.viewContext

managedContext.delete(people[indexPath.row])

do {

try managedContext.save()

people.remove(at: indexPath.row)

tableViewOutlet.deleteRows(at: [indexPath], with: .fade)

} catch {

let saveError = error as NSError

print(saveError)

}

let’s take an example –

step 1: create a new project, and select use the core data option.

step 2: create a file for core data,

click on CoreData.xcdatamodeld option
Click on the Add Entity option
And add your data which you need to save in core data

step 3: it looks like this

Click on the plus icon
enter your data name which you want to store.

code of the example – create a file for the alert box i.e ButtonBar.swift class

import Foundation
import UIKit
import CoreData

class ButtonAlert: UIViewController{
    let userDefault = UserDefaults.standard
    var onEdit : ((_ tableReload : Bool, _ nameText : String, _ ageText : String, _ dob : String ) -> Void)?
   
    func alertAction(controller: UIViewController, value: Int, nameString: String){
    //1. Create the alert controller.
          let alert = UIAlertController(title: "", message: "Enter your details", preferredStyle: .alert)
          
          //2. Add the text field. You can configure it however you need.
          alert.addTextField { (nameTextField) -> Void in
              nameTextField.placeholder = "Enter your name."
          }
          alert.addTextField { (ageTextField) -> Void in
                     ageTextField.placeholder = "Enter your age."
                 }
          alert.addTextField { (dobTextField) -> Void in
                     dobTextField.placeholder = "Enter your date of birth."
                 }
         
          
          //3. Grab the value from the text field, and print it when the user clicks OK.
          alert.addAction(UIAlertAction(title: "OK", style: .default, handler: { [weak alert] (action) -> Void in
              let textField:String = ((alert?.textFields![0])?.text!)!
              let textField1:String = ((alert?.textFields![1])?.text!)!
              let textField2:String = ((alert?.textFields![2])?.text!)!
             
              
                  // realm.deleteAll()
                  if textField != "" && textField1 != "" && textField2 != ""{
                   
                    self.onEdit!(true, textField, textField1, textField2)
                   
                  }else{
                      print("add your missing details")
                  }
              
              
          }))
          alert.addAction(UIAlertAction(title: "Cancel", style: .default, handler: nil))
          
          // 4. Present the alert.
          controller.present(alert, animated: true, completion: nil)
}

import Foundation

import UIKit

import CoreData

class ButtonAlert: UIViewController{

let userDefault = UserDefaults.standard

var onEdit : ((_ tableReload : Bool, _ nameText : String, _ ageText : String, _ dob : String ) -> Void)?

func alertAction(controller: UIViewController, value: Int, nameString: String){

//1. Create the alert controller.

let alert = UIAlertController(title: "", message: "Enter your details", preferredStyle: .alert)

//2. Add the text field. You can configure it however you need.

alert.addTextField { (nameTextField) -> Void in

nameTextField.placeholder = "Enter your name."

}

alert.addTextField { (ageTextField) -> Void in

ageTextField.placeholder = "Enter your age."

}

alert.addTextField { (dobTextField) -> Void in

dobTextField.placeholder = "Enter your date of birth."

}

//3. Grab the value from the text field, and print it when the user clicks OK.

alert.addAction(UIAlertAction(title: "OK", style: .default, handler: { [weak alert] (action) -> Void in

let textField:String = ((alert?.textFields![0])?.text!)!

let textField1:String = ((alert?.textFields![1])?.text!)!

let textField2:String = ((alert?.textFields![2])?.text!)!

// realm.deleteAll()

if textField != "" && textField1 != "" && textField2 != ""{

self.onEdit!(true, textField, textField1, textField2)

}else{

print("add your missing details")

}

}))

alert.addAction(UIAlertAction(title: "Cancel", style: .default, handler: nil))

// 4. Present the alert.

controller.present(alert, animated: true, completion: nil)

}

2. create a viewController class

import UIKit
import CoreData

class ViewController: UIViewController {
    
    @IBOutlet weak var tableViewOutlet: UITableView!
    
    var people: [NSManagedObject] = []
    var buttonAlertBar = ButtonAlert()
    let appDelegate = UIApplication.shared.delegate as? AppDelegate
    override func viewDidLoad() {
        super.viewDidLoad()
       
    }
    
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        
        //1
        let managedContext =
            appDelegate!.persistentContainer.viewContext
        //2
        let fetchRequest =
            NSFetchRequest<NSManagedObject>(entityName: "Person")
        //3
        do {
            people = try managedContext.fetch(fetchRequest)
        } catch let error as NSError {
            print("Could not fetch. \(error), \(error.userInfo)")
        }
    }
    @IBAction func plusButton(_ sender: Any) {
        buttonAlertBar.alertAction(controller: self, value: 0, nameString: "" )
        buttonAlertBar.onEdit = { [weak self] (tableReload: Bool, nameText: String, ageText: String, dob: String ) in
            self?.save(name: nameText, age: ageText, dob: dob)
            self?.tableViewOutlet.reloadData()
            }
        
    }
    func save(name: String, age: String, dob: String) {
        // 1
        let managedContext =
            appDelegate!.persistentContainer.viewContext
        // 2
        let entity =
            NSEntityDescription.entity(forEntityName: "Person",
                                       in: managedContext)!
        let person = NSManagedObject(entity: entity,
                                     insertInto: managedContext)
        // 3
        person.setValue(name, forKeyPath: "name")
        person.setValue(age, forKey: "age")
        person.setValue(dob, forKey: "dob")
        // 4
        do {
            try managedContext.save()
            people.append(person)
        } catch let error as NSError {
            print("Could not save. \(error), \(error.userInfo)")
        }
    }
  

extension ViewController: UITableViewDataSource,UITableViewDelegate{
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return people.count
    }
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let person = people[indexPath.row]
        let myCell = tableViewOutlet.dequeueReusableCell(withIdentifier: "CoreDataTVTableViewCell") as! CoreDataTVTableViewCell
        myCell.nameLabel?.text =  "Name :" + (person.value(forKey: "name") as! String)
        myCell.ageLabel?.text = "Age :" + (person.value(forKeyPath: "age") as! String)
        myCell.dateOfBirthLabel?.text = "DOB :" + (person.value(forKeyPath: "dob") as! String)
        myCell.tag = indexPath.row
        
        return myCell
    }
    func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
        return 120
    }
    func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCell.EditingStyle, forRowAt indexPath: IndexPath) {
        
        if editingStyle == .delete {
            let managedContext =
                appDelegate!.persistentContainer.viewContext
            
            managedContext.delete(people[indexPath.row])
            
            
            do {
                try  managedContext.save()
                
                people.remove(at: indexPath.row)
                
                tableViewOutlet.deleteRows(at: [indexPath], with: .fade)
            } catch {
                let saveError = error as NSError
                print(saveError)
            }
        }
    }
}

100

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import UIKit

import CoreData

class ViewController: UIViewController {

@IBOutlet weak var tableViewOutlet: UITableView!

var people: [NSManagedObject] = []

var buttonAlertBar = ButtonAlert()

let appDelegate = UIApplication.shared.delegate as? AppDelegate

override func viewDidLoad() {

super.viewDidLoad()

}

override func viewWillAppear(_ animated: Bool) {

super.viewWillAppear(animated)

//1

let managedContext =

appDelegate!.persistentContainer.viewContext

//2

let fetchRequest =

NSFetchRequest<NSManagedObject>(entityName: "Person")

//3

do {

people = try managedContext.fetch(fetchRequest)

} catch let error as NSError {

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

}

@IBAction func plusButton(_ sender: Any) {

buttonAlertBar.alertAction(controller: self, value: 0, nameString: "" )

buttonAlertBar.onEdit = { [weak self] (tableReload: Bool, nameText: String, ageText: String, dob: String ) in

self?.save(name: nameText, age: ageText, dob: dob)

self?.tableViewOutlet.reloadData()

}

func save(name: String, age: String, dob: String) {

// 1

let managedContext =

appDelegate!.persistentContainer.viewContext

// 2

let entity =

NSEntityDescription.entity(forEntityName: "Person",

in: managedContext)!

let person = NSManagedObject(entity: entity,

insertInto: managedContext)

// 3

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

person.setValue(age, forKey: "age")

person.setValue(dob, forKey: "dob")

// 4

do {

try managedContext.save()

people.append(person)

} catch let error as NSError {

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

}

extension ViewController: UITableViewDataSource,UITableViewDelegate{

func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {

return people.count

}

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

let person = people[indexPath.row]

let myCell = tableViewOutlet.dequeueReusableCell(withIdentifier: "CoreDataTVTableViewCell") as! CoreDataTVTableViewCell

myCell.nameLabel?.text = "Name :" + (person.value(forKey: "name") as! String)

myCell.ageLabel?.text = "Age :" + (person.value(forKeyPath: "age") as! String)

myCell.dateOfBirthLabel?.text = "DOB :" + (person.value(forKeyPath: "dob") as! String)

myCell.tag = indexPath.row

return myCell

}

func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {

return 120

}

func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCell.EditingStyle, forRowAt indexPath: IndexPath) {

if editingStyle == .delete {

let managedContext =

appDelegate!.persistentContainer.viewContext

managedContext.delete(people[indexPath.row])

do {

try managedContext.save()

people.remove(at: indexPath.row)

tableViewOutlet.deleteRows(at: [indexPath], with: .fade)

} catch {

let saveError = error as NSError

print(saveError)

}

I am attaching some screen of my code for a better understanding

Conclusion –

In this blog, we have discussed how to save, update, create and delete the data in the database by using The CRUD operation with core data

I hope this blog will help you in getting some basic knowledge about the CRUD operation with core data.

Thanks for reading!