ios - 当您尝试删除一个项目时我的应用程序崩溃并且它不显示所有三个警报字段？

Question

图片

更新的代码 xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx 出现错误，然后当我运行时出现致命错误，不知道为什么会这样，但这是在你们帮助后更新的代码。请告诉我xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

        import UIKit

let defaults = UserDefaults(suiteName: "com.Saving.Data")

struct Product: Codable {
    var title: String
    var price: String
    var salePrice: String
}

class ViewController: UIViewController {

    @IBOutlet weak var tableView: UITableView!

    var items: [(item: String?, price: String?, salesPrice: String?)] = []

    override func viewDidLoad() {
        super.viewDidLoad()
        getData()
    }
    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(true)
        getData()
    }

    override func viewDidDisappear(_ animated: Bool) {
        super.viewDidDisappear(true)
        storeData()
    }
    override var prefersStatusBarHidden: Bool {
        return true
    }

    @IBAction func addButtonTapped(_ sender: Any) {
        let alert = UIAlertController(title: "Product Information", message: nil, preferredStyle: .alert)
            alert.addTextField { (itemTF) in
                itemTF.placeholder = "Item"
            }

            alert.addTextField { (textField) in
                textField.placeholder = "Price"
            }

            alert.addTextField { (textField) in
                textField.placeholder = "Sale Price"
            }

            let action = UIAlertAction(title: "Add", style: .default) { (_) in

                var product : (item: String, price: String, salesPrice: String) = ("","","")

                if let textField1 = alert.textFields?[0], let text = textField1.text {
                    print(text)
                    product.item = text

                }

                if let textField2 = alert.textFields?[1], let text = textField2.text {
                    print(text)
                     product.price = text

                }

                if let textField3 = alert.textFields?[2], let text = textField3.text {
                    print(text)
                    product.salesPrice = text

                }
                self.add(product)
            }

            alert.addAction(action)
            present(alert, animated: true)
            storeData()
        }

       func add(_ product: (item: String, price: String, salesPrice: String)) {
            let index = 0
            items.insert(product, at: index)

            let indexPath = IndexPath(row: index, section: 0)
            tableView.insertRows(at: [indexPath], with: .left)
            storeData()
        }


     func storeData() {

           if let data = try? PropertyListEncoder().encode(items) {
               defaults?.set(data, forKey: "savedData")
           }
       }

       func getData() {

           if let data = defaults?.data(forKey: "savedData") {
               items = try! PropertyListDecoder().decode([Product].self, from: data)
           }
       }



}

extension ViewController: UITableViewDataSource {
    func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return items.count
    }

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

        let cell = UITableViewCell()
        let product = items[indexPath.row]
        cell.textLabel?.text = product.item
        print(product.price ?? "")
        print(product.salesPrice ?? "")

        cell.contentView.backgroundColor = UIColor(red:0.92, green:0.92, blue:0.92, alpha:1.0)
        cell.textLabel?.textColor = UIColor(red:0.13, green:0.13, blue:0.13, alpha:1.0)
        tableView.separatorColor = UIColor(red:0.92, green:0.92, blue:0.92, alpha:1.0)


        return cell
    }

    func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCell.EditingStyle, forRowAt indexPath: IndexPath) {
        guard editingStyle == .delete else { return }
        items.remove(at: indexPath.row)
        tableView.reloadData()
        storeData()
    }
}

标签： iosswiftuitableview

Answer 1

要显示产品的所有信息，如名称、价格、销售价格，您必须创建一个Class或Structure或Tuple。它需要确认Codable Protocol 才能保存到UserDefaults。

struct Product: Codable {
    var title: String
    var price: String
    var salePrice: String
}

然后，您必须使用几个（这次是 3 个）UILabel和适当的AutoLayoutConstraints创建一个自定义UITableViewCell来显示Product的所有信息。

这是完整的代码

import UIKit

struct Product: Codable {
    var title: String
    var price: String
    var salePrice: String
}

let defaults = UserDefaults(suiteName: "savedData")

class ViewController: UIViewController {

    @IBOutlet weak var tableView: UITableView!

    var items = [Product]()

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.

        navigationItem.rightBarButtonItem = UIBarButtonItem(barButtonSystemItem: .add, target: self, action: #selector(addButtonPressed))

        tableView.delegate = self
        tableView.dataSource = self

        getData()
    }

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        getData()
    }

    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        storeData()
    }

    @objc func addButtonPressed() {

        let alert = UIAlertController(title: "Product Information", message: nil, preferredStyle: .alert)

        alert.addTextField { (itemTF) in
            itemTF.placeholder = "Item"
        }

        alert.addTextField { (textField) in
            textField.placeholder = "Price"
        }

        alert.addTextField { (textField) in
            textField.placeholder = "Sale Price"
        }

        let addAction = UIAlertAction(title: "Add", style: .default) { (_) in

            let firstTextField = alert.textFields![0] as UITextField
            let secondTextField = alert.textFields![1] as UITextField
            let thirdTextField = alert.textFields![2] as UITextField

            let product = Product(title: firstTextField.text!, price: secondTextField.text!, salePrice: thirdTextField.text!)

            self.items.append(product)
            self.tableView.reloadData()
        }
        let cancelAction = UIAlertAction(title: "Cancel", style: .cancel, handler: nil)

        alert.addAction(addAction)
        alert.addAction(cancelAction)
        present(alert, animated: true)
    }

    func add(_ product: Product) {
            let index = 0
            items.insert(product, at: index)

            let indexPath = IndexPath(row: index, section: 0)
            tableView.insertRows(at: [indexPath], with: .left)
            storeData()
        }



    func storeData() {

        if let data = try? PropertyListEncoder().encode(items) {
            defaults?.set(data, forKey: "savedData")
        }
    }

    func getData() {

        if let data = defaults?.data(forKey: "savedData") {
            items = try! PropertyListDecoder().decode([Product].self, from: data)
        }
    }
}

extension ViewController: UITableViewDataSource, UITableViewDelegate {

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return items.count
    }

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

        let cell = tableView.dequeueReusableCell(withIdentifier: "CustomCell", for: indexPath) as! CustomCell
        cell.data = items[indexPath.row]
        return cell
    }

    func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCell.EditingStyle, forRowAt indexPath: IndexPath) {
        guard editingStyle == .delete else { return }
        items.remove(at: indexPath.row)
        self.tableView.reloadData()
        storeData()
    }
}

class CustomCell: UITableViewCell {

    @IBOutlet weak var titleLabel: UILabel!
    @IBOutlet weak var priceLabel: UILabel!
    @IBOutlet weak var salePriceLabel: UILabel!

    var data: Product? {
        didSet {
            guard let data = data else {return}

            titleLabel.text = data.title
            priceLabel.text = data.price
            salePriceLabel.text = data.salePrice

        }
    }

    override func awakeFromNib() {
        super.awakeFromNib()
    }
}