保存/读取CoreData关系Swift 3
问题描述：
我正在为学习目的制作一个预算应用程序，并且有关于在CoreData中存储和获取实体的一些问题。保存/读取CoreData关系Swift 3
我有两个实体“预算”和“费用”。
每个预算都有自己的费用。作为一个例子，我可以有一个'娱乐'的预算，它可以有诸如'保龄球'和'电影'等费用。
我可以创建一个预算并保存它。然后增加费用。
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()
我然后检索费的征收，并在TableView中
// 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
到目前为止好显示商店名称。我的问题是，当我存储费用时，它存储在一个集合中。这意味着当我检索该集合并将它转换为数组时，该顺序是随机的。
我想要的是存储费用，并检索它们，以便我可以在TableView中以FIFO顺序显示费用。换句话说，我在预算中添加的第一笔开支应该是表格视图中的第一个元素，依此类推。
答
可能有几种方法来实现这一点。最直接的方法是使用expense的Ordered关系。在DataModel中编辑
要做到这一点，
- 打开
expense关系属性。 - 检查有序选项
然后budget.expense将不Set，但OrderedSet，你将不再需要将其转换为Array，但指数直接访问它。
答
的viewController 1： =====================>
进口CoreData
类的ViewController：UIViewController的{
@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
}
}
的viewController 2：
=====================>
CLAS小号ViewController2：UIViewController中，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)
}
覆盖FUNC准备（对于SEGUE：UIStoryboardSegue，发件人：任何）
{
if let newlabel = txt_pwd.text
{
str1 = newlabel as NSString
}
}
美丽！谢谢！ – Alberto93