Saving/Fetching CoreData Relationships Swift 3 - ios

Question

I am making a budgeting app for the purposes of learning and I have a few questions about storing and fetching entities in CoreData.
I have two entities "Budget" and "Expense".
Every Budget has its own Expenses. As an example I can have an 'Entertainment' budget and it can have expenses such as 'Bowling' and 'Movies' etc.
I can create a Budget and save it. And then add expenses to it.
let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
let expense = Expense(context: context)
.
. // Filling out the expense here
.
budget?.addToExpense(expense)
(UIApplication.shared.delegate as! AppDelegate).saveContext()
I then retrieve the collection of Expenses and display the store name in a TableView
// Inside cellForRowAt
let cell = UITableViewCell(style: .default, reuseIdentifier: "cell")
let myArray = Array((budget?.expense)!)
cell.textLabel?.text = (myArray[indexPath.row] as! Expense).store
return cell
So far so good. My issue is that when I store an expense it is stored in a Set. Which means the order is random when I retrieve that set and typecast it into an Array.
What I want is to store the Expenses and retrieve them in such a way that I can display the expenses in a FIFO order in the TableView. In other words the first expense I add in the budget should be the first element in the table view and so on and so forth.

Answer 1

There could be several ways to achieve that. The most straightforward would be to use Ordered relation for expense.
To do that,
Open expense relationship properties in DataModel editor.
Check Ordered option
Then budget.expense will be not Set, but OrderedSet, and you won't need to convert it to Array, but access it directly by index.

Answer 2

VIEWCONTROLLER 1:
=====================>
import CoreData
class ViewController: UIViewController {
#IBOutlet weak var txt_user: UITextField!
#IBOutlet weak var txt_password: UITextField!
var result = NSArray()
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
txt_password.isSecureTextEntry = true
}
#IBAction func login_action(_ sender: Any)
{
if(txt_user.text == "" || txt_password.text == "")
{
let alert = UIAlertController(title: "info", message: "fields are empty", preferredStyle: .alert)
let ok = UIAlertAction(title: "OK", style: .default, handler: nil)
alert.addAction(ok)
self.present(alert, animated: true, completion: nil)
}
else
{
self.CheckForUserNameAndPasswordMatch(empName: txt_user.text! , empPwd: txt_password.text!)
}
}
func CheckForUserNameAndPasswordMatch(empName:String,empPwd:String)
{
let app = UIApplication.shared.delegate as! AppDelegate
let context = app.persistentContainer.viewContext
let fetchdata = NSFetchRequest<NSManagedObject>(entityName: "Employee")
let predicate = NSPredicate(format: "empName = %#",empName)
fetchdata.predicate = predicate
do
{
self.result = try context.fetch(fetchdata as! NSFetchRequest<NSFetchRequestResult>)as NSArray
if result.count>0
{
let objcetEntity = result.firstObject as! Employee
if objcetEntity.empName == empName && objcetEntity.empPwd == empPwd
{
print("Login Successfully")
// Entered Username & password matched
}
else
{
print("Wrong password/username")
//Wrong password/username
}
}
}
catch let error as NSError
{
print("error",error.localizedDescription)
}
}
#IBAction func unwindToVC1(sender:UIStoryboardSegue)
{
if sender.source is ViewController2
{
let secvc = sender.source as! ViewController2
txt_password.text = secvc.str1! as String
}
}
VIEWCONTROLLER 2:
=====================>
class ViewController2: UIViewController ,UITextFieldDelegate{
#IBOutlet weak var txt_name: UITextField!
#IBOutlet weak var txt_mail: UITextField!
#IBOutlet weak var txt_pwd: UITextField!
#IBOutlet weak var txt_cpwd: UITextField!
#IBOutlet weak var txt_phone: UITextField!
#IBOutlet weak var err: UILabel!
var str1:NSString!
var str2:NSString!
//var update:NSManagedObject!
override func viewDidLoad() {
super.viewDidLoad()
/*if(update != nil)
{
txt_name.text = update.value(forKey: "empName") as? String
txt_mail.text = update.value(forKey: "empMail") as? String
txt_pwd.text = update.value(forKey: "empPwd") as? String
txt_cpwd.text = update.value(forKey: "empCpwd") as? String
txt_phone.text = update.value(forKey: "empPhone") as? String
}*/
txt_pwd.isSecureTextEntry = true
txt_cpwd.isSecureTextEntry = true
}
override func viewWillAppear(_ animated: Bool)
{
txt_name.becomeFirstResponder()
}
#IBAction func regis_clicked(_ sender: Any)
{
if(txt_name.text == "" || txt_mail.text == "" || txt_pwd.text == "" || txt_cpwd.text == "" || txt_phone.text == "" )
{
let alert = UIAlertController(title: "information", message: "fields are empty", preferredStyle: .alert)
let ok = UIAlertAction(title: "OK", style: .default, handler:
{
(actionsheet) in
if(self.txt_name.text == "")
{
self.txt_name.becomeFirstResponder()
}
if(self.txt_mail.text == "")
{
self.txt_mail.becomeFirstResponder()
}
if(self.txt_pwd.text == "")
{
self.txt_pwd.becomeFirstResponder()
}
if(self.txt_cpwd.text == "")
{
self.txt_cpwd.becomeFirstResponder()
}
if(self.txt_phone.text == "")
{
self.txt_phone.becomeFirstResponder()
}
})
let cancel = UIAlertAction(title: "cancel", style: .default, handler: nil)
alert.addAction(ok)
alert.addAction(cancel)
self.present(alert, animated: true, completion: nil)
}
else if(txt_pwd.text != txt_cpwd.text)
{
let alert1 = UIAlertController(title: "information", message: "password mismatched", preferredStyle: .alert)
let ok = UIAlertAction(title: "OK", style: .default, handler:nil)
let cancel = UIAlertAction(title: "cancel", style: .default, handler: nil)
alert1.addAction(ok)
alert1.addAction(cancel)
self.present(alert1, animated: true, completion: nil)
}
else
{
let app = UIApplication.shared.delegate as! AppDelegate
let context = app.persistentContainer.viewContext
let newuser = NSEntityDescription.insertNewObject(forEntityName: "Employee", into: context)
newuser.setValue(txt_name.text, forKey: "empName")
newuser.setValue(txt_mail.text, forKey: "empMail")
newuser.setValue(txt_pwd.text, forKey: "empPwd")
newuser.setValue(txt_cpwd.text, forKey: "empCpwd")
newuser.setValue(txt_phone.text, forKey: "empPhone")
do
{
try context.save()
}
catch let error as NSError
{
print("error",error.localizedDescription)
}
}
// self.navigationController?.popViewController(animated: true)
performSegue(withIdentifier: "unwind", sender: self)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?)
{
if let newlabel = txt_pwd.text
{
str1 = newlabel as NSString
}
}