如何在 Swift 中获取表格视图单元格数据的总和？

Question

我正在尝试将所有金额数据相加并发送到不同的表格视图单元格。我想我需要先将 String 转换为 Double 才能执行此操作，但我也不确定如何执行此操作。有谁知道如何获取数据总和并将其呈现在其他地方？我对 swift 很陌生，无法弄清楚我需要在哪里编写这段代码。

import Foundation

struct Income: Codable {
    var name: String
    var amount: String

    init(name: String, amount: String) {
        self.name = name
        self.amount = amount
    }


    static let DocumentsDirectory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!

    static let ArchiveURL = DocumentsDirectory.appendingPathComponent("incomes").appendingPathExtension("plist")

    static func loadSampleIncomes() -> [Income] {
        return [
            Income(name: "Main Income", amount: "0"),
            Income(name: "Secondary Income", amount: "0"),
            Income(name: "Interest Income", amount: "0")]

    }

    static func saveToFile(incomes: [Income]) {
           let propertyListEncoder = PropertyListEncoder()
           let codedIncomes = try? propertyListEncoder.encode(incomes)

           try? codedIncomes?.write(to: ArchiveURL, options: .noFileProtection)

    }

    static func loadFromFile() -> [Income]? {
            guard let codedIncomes = try? Data(contentsOf: ArchiveURL) else { return nil }

            let propertyListDecoder = PropertyListDecoder()

            return try? propertyListDecoder.decode(Array<Income>.self, from: codedIncomes)
    }

}

import UIKit

class IncomeTableViewController: UITableViewController {

var incomes: [Income] = []


override func viewDidLoad() {
    super.viewDidLoad()

    tableView.tableFooterView = UIView(frame: CGRect.zero)

if let savedIncomes = Income.loadFromFile() {
        incomes = savedIncomes
    } else {
        incomes = Income.loadSampleIncomes()
    }
}


override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)

    tableView.reloadData()
}

// table view data source

override func numberOfSections(in tableView: UITableView) -> Int {
     return 1
}

override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
       if section == 0 {
           return incomes.count
       } else {
           return 0
       }
}

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

    let cell = tableView.dequeueReusableCell(withIdentifier: "incomeCell", for: indexPath) as! IncomeTableViewCell

    let income = incomes[indexPath.row]

    cell.update(with: income)
    cell.showsReorderControl = true

    return cell

}



// MARK: - Table view delegate

override func tableView(_ tableView: UITableView, editingStyleForRowAt indexPath: IndexPath) -> UITableViewCell.EditingStyle {
    return .delete

}

override func tableView(_ tableView: UITableView, commit
    editingStyle: UITableViewCell.EditingStyle, forRowAt indexPath:
    IndexPath) {
        if editingStyle == .delete {
            incomes.remove(at: indexPath.row)
            tableView.deleteRows(at: [indexPath], with: . automatic)
            Income.saveToFile(incomes: incomes)
       }
}

override func tableView(_ tableView: UITableView, moveRowAt fromIndexPath: IndexPath, to: IndexPath) {
      let movedIncome = incomes.remove(at: fromIndexPath.row)
      incomes.insert(movedIncome, at: to.row)
      tableView.reloadData()

}

@IBAction func editButtonTapped(_ sender: UIBarButtonItem) {
    let tableViewEditingMode = tableView.isEditing

    tableView.setEditing(!tableViewEditingMode, animated: true)
}

// Navigation

@IBAction func unwindToIncomeTableView(segue:UIStoryboardSegue) {
    guard segue.identifier == "saveIncomeUnwind",
    let sourceViewController = segue.source as? AddEditIncomeTableViewController,

    let income = sourceViewController.income else { return }
        if let selectedIndexPath = tableView.indexPathForSelectedRow {
            incomes[selectedIndexPath.row] = income
            tableView.reloadRows(at: [selectedIndexPath],
            with: .none)
        } else {
            let newIndexPath = IndexPath(row: incomes.count, section: 0)
            incomes.append(income)
            tableView.insertRows(at: [newIndexPath], with: .automatic)
        }

        Income.saveToFile(incomes: incomes)
}

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "EditIncome" {
        let indexPath = tableView.indexPathForSelectedRow!
        let income = incomes[indexPath.row]
        let navController = segue.destination as! UINavigationController
        let addEditIncomeTableViewController = navController.topViewController as! AddEditIncomeTableViewController

        addEditIncomeTableViewController.income = income
    }
}


}

import UIKit

class AddEditIncomeTableViewController: UITableViewController {

    @IBOutlet weak var saveButton: UIBarButtonItem!
    @IBOutlet weak var incomeNameTextField: UITextField!
    @IBOutlet weak var incomeAmountTextField: UITextField!

    var income: Income?

    override func viewDidLoad() {
        super.viewDidLoad()

        if let income = income {
            incomeNameTextField.text = income.name
            incomeAmountTextField.text = income.amount


        }

        updateSaveButtonState()
    }



    override func prepare(for segue: UIStoryboardSegue, sender:
      Any?) {
          super.prepare(for: segue, sender: sender)

          guard segue.identifier == "saveIncomeUnwind" else { return }

          let name = incomeNameTextField.text ?? ""
          let amount = incomeAmountTextField.text ?? ""
          income = Income(name: name, amount: amount)
    }

    func updateSaveButtonState() {
            let nameText = incomeNameTextField.text ?? ""
            let amountText = incomeAmountTextField.text ?? ""
            saveButton.isEnabled = !nameText.isEmpty && !amountText.isEmpty
        }

    @IBAction func textEditingChanged(_ sender: UITextField) {
    updateSaveButtonState()


    }


}

这是我希望在其中显示新数据的表格视图控制器。

    import UIKit

    class BudgetHomeTableViewController: UITableViewController {

    var incomes: [Income] = []
    var expenses: [Expense] = []

    override func viewDidLoad() {
        super.viewDidLoad()

        tableView.tableFooterView = UIView(frame: CGRect.zero)

        if let savedIncomes = Income.loadFromFile() {
            incomes = savedIncomes
        } else {
            incomes = Income.loadSampleIncomes()
        }

        if let savedExpenses = Expense.loadFromFile() {
            expenses = savedExpenses
        } else {
            expenses = Expense.loadSampleExpenses()
        } 
    }
    }

这是专门显示数据的单元格

    import UIKit

    class BugetBalanceCell: UITableViewCell {

    @IBOutlet weak var budgetBalanceText: UILabel!

    var incomes: [Income] = []
    var expenses: [Expense] = []




    override func awakeFromNib() {
        super.awakeFromNib()

     let incomeTotal = incomes.map({Double($0.amount) ?? 0}).reduce(0, +)
     let expenseTotal = expenses.map({Double($0.amount) ?? 0}).reduce(0, +)

     let balance = incomeTotal - expenseTotal


    }




    override func setSelected(_ selected: Bool, animated: Bool) {
        super.setSelected(selected, animated: animated)

        // Configure the view for the selected state
    }
    }

Answer 1

首先定义你的收入、支出数组并加载数据

var incomes: [Income] = []
var expenses: [Income] = []


if let savedIncomes = Income.loadFromFile() {
    incomes = savedIncomes
} else {
    incomes = Income.loadSampleIncomes()
}

//do the same thing for load data to expenses array

你可以得到你的余额 = 收入 - 支出使用

let incomeTotal = incomes.map({Double($0.amount) ?? 0}).reduce(0, +)
let expenseTotal = expenses.map({Double($0.amount) ?? 0}).reduce(0, +)

let balance = incomeTotal - expenseTotal

在下一个表格视图控制器中您想显示的位置使用此值

Answer 2

(income as NSArray).valueForKeyPath("@sum.self")