【发布时间】：2018-09-05 00:27:17
【问题描述】：
我是 Xcode 和 Swift 的初学者，我目前正在创建一个应用程序，用户在应用程序上添加一个人，然后纠正他们欠那个人或那个人欠他/她的钱。
注意：我已经使用核心数据来存储所有值
我实际上想在开关打开和关闭时更改变量的值。例如，在下面我希望“数量”在开关打开时为负数，在开关关闭时为正数。此外，当我尝试执行此操作并将数量变量发送到前一个视图控制器时，我无法根据 UISwitch 发送值，因为它始终显示为正值。我正在尝试从过去 3 天中找到解决此问题的方法，因此您能帮帮我吗？提前非常感谢
欠视图控制器
import UIKit
class NewOweTableViewController: UIViewController {
@IBOutlet weak var titleTextField: UITextField!
@IBOutlet weak var locationTextField: UITextField!
@IBOutlet weak var amountTextField: UITextField!
@IBOutlet weak var datePicker: UIDatePicker!
let context = (UIApplication.shared.delegate as!
AppDelegate).persistentContainer.viewContext
var owe: Owe?
var dataInfo: [Owe] = []
override func viewDidLoad() {
super.viewDidLoad()
self.navigationController?.navigationBar.viewWithTag(1)?.isHidden = true
let saveBTN = UIBarButtonItem(barButtonSystemItem:UIBarButtonSystemItem.save, target:self,
action: #selector(saveButtonTapped(_:)))
let deleteBTN = UIBarButtonItem(barButtonSystemItem:UIBarButtonSystemItem.trash, target:self,
action: #selector(deleteButtonTapped(_:)))
self.navigationItem.rightBarButtonItems = [saveBTN, deleteBTN]
if !dataInfo.isEmpty {
titleTextField.text = dataInfo[0].name
amountTextField.text = (NSString(format: "%.2f", (dataInfo[0].amount) as CVarArg) as String)
locationTextField.text = dataInfo[0].location
datePicker.date = dataInfo[0].date!
}
}
@objc func saveButtonTapped(_ sender: UIButton){
if !dataInfo.isEmpty{
let data = dataInfo[0]
data.name = titleTextField.text
data.amount = Double(amountTextField.text!)!
data.location = locationTextField.text
data.date = datePicker.date
}
else if titleTextField.text == "" || amountTextField.text == "" || locationTextField.text == "" {
return
}
else{
let data = Owe(context: context)
data.name = titleTextField.text
data.amount = Double(amountTextField.text!)!
data.location = locationTextField.text
data.date = datePicker.date
}
do {
try context.save()
navigationController?.popViewController(animated: true)
} catch {
let nserror = error as NSError
fatalError("Unresolved error \(nserror), \(nserror.userInfo)")
}
}
@objc func deleteButtonTapped(_ sender: UIButton){
if !dataInfo.isEmpty{
let data = dataInfo[0]
context.delete(data)
do {
try context.save()
navigationController?.popViewController(animated: true)
} catch {
let nserror = error as NSError
fatalError("Unresolved error \(nserror), \(nserror.userInfo)")
}
}
}
@IBAction func oweSwitch(_ sender: UISwitch) {
if sender.isOn {
owe?.amount = (owe?.amount)! * (-1)
amountTextField.textColor = UIColor.green
} else {
owe?.amount = (owe?.amount)! * (1)
amountTextField.textColor = UIColor.red
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
上一个视图控制器
import UIKit
class PersonDetailTableViewController: UITableViewController {
let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
var totalLabel: UILabel?
var person: People?
var owe: Owe?
@IBOutlet var personTable: UITableView!
var dataInfo: [Owe] = []
var selectedObject: [Owe] = []
var balanceAmount = "Balance: "
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return (dataInfo.count)
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = personTable
.dequeueReusableCell(withIdentifier: "detailsCell", for: indexPath)
cell.textLabel?.text = dataInfo[indexPath.row].name
cell.detailTextLabel?.text = "₹ \(dataInfo[indexPath.row].amount)"
if dataInfo[indexPath.row].amount < 0 {
cell.detailTextLabel?.textColor = UIColor.red
} else {
cell.detailTextLabel?.textColor = UIColor.green
}
return cell
}
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
selectedObject = [dataInfo[indexPath.row]]
performSegue(withIdentifier: "addOweDetails", sender: nil)
tableView.deselectRow(at: indexPath, animated: true)
}
override func viewDidLoad() {
super.viewDidLoad()
getData()
personTable.dataSource = self
addTotalToNav()
print(dataInfo as Any)
}
// MARK: - Table view data source
func addTotalToNav() -> Void {
if let navigationBar = self.navigationController?.navigationBar {
let totalFrame = CGRect(x: 10, y: 0, width: navigationBar.frame.width/2, height: navigationBar.frame.height)
totalLabel = UILabel(frame: totalFrame)
totalLabel?.text = balanceAmount
totalLabel?.tag = 1
totalLabel?.font = UIFont.boldSystemFont(ofSize: 14)
totalLabel?.textColor = UIColor.red
// navigationBar.large = totalLabel?.text
self.title = totalLabel?.text
}
}
func getData() -> Void {
do{
dataInfo = try context.fetch(Owe.fetchRequest())
var total:Double = 0.00
for i in 0 ..< dataInfo.count {
total += dataInfo[i].amount as! Double
}
balanceAmount = "Balance: ₹" + (NSString(format: "%.2f", total as CVarArg) as String)
}
catch{
print("Fetching Failed")
}
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
let vc = segue.destination as! NewOweTableViewController
vc.dataInfo = selectedObject
selectedObject.removeAll()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
getData()
personTable.reloadData()
if (self.navigationController?.navigationBar.viewWithTag(1)?.isHidden == true){
self.navigationController?.navigationBar.viewWithTag(1)?.removeFromSuperview()
addTotalToNav()
}
}
}
欠的核心数据
import UIKit
import CoreData
@objc(Owe)
public class Owe: NSManagedObject {
var date: Date? {
get{
return rawDate as Date?
}
set {
rawDate = newValue as NSDate?
}
}
convenience init?(name: String?, location: String?, amount: Double, date: Date?) {
let appDelegate = UIApplication.shared.delegate as? AppDelegate
guard let context = appDelegate?.persistentContainer.viewContext
else {
return nil
}
self.init(entity: Owe.entity(), insertInto: context)
self.name = name
self.location = location
self.amount = amount
self.date = date
}
}
【问题讨论】：
-
如何将数据从 oweVC 发送到 previousVC ??
-
amount逻辑有缺陷。你需要类似owe?.amount = abs(owe.amount ?? 0) * (sender.isOn ? 1 : - 1) -
更重要的是，
owe变量永远不会被初始化：它总是 nil。
标签： ios swift xcode core-data uiswitch