How can I update the text values in the UITextfield in a reusable tableView cell, with different values in each cell

Question

I am making a currency converter that updates currencies simultaneously as you type. The currencies are held in a tableView and the cell is a custom cell.

I want to be able to type into one cell, and see all the other cells update with the value from the conversion calculation. The calculation works, but I am not sure how to get the data back into the correct cells, as essentially there is only one as it is a reusable cell.

Here is the cell class, (I am just showing the input to keep things clear.):

class PageCell: UITableViewCell {

let cellCalcInput = UITextField()

func configureCustomCell() {

    contentView.addSubview(cellCalcInput)
    cellCalcInput.translatesAutoresizingMaskIntoConstraints = false
    cellCalcInput.rightAnchor.constraint(equalTo: contentView.rightAnchor, constant: -10).isActive = true
    cellCalcInput.centerYAnchor.constraint(equalTo: contentView.centerYAnchor).isActive = true
    cellCalcInput.font = secondFont?.withSize(18)
    cellCalcInput.textColor = .white
    cellCalcInput.placeholder = "Enter an amount"
    cellCalcInput.keyboardType = .decimalPad
    cellCalcInput.borderStyle = .roundedRect
    cellCalcInput.backgroundColor = .clear

    cellCalcInput.isHidden = true
    self.backgroundColor = .darkGray
    contentView.contentMode = .scaleAspectFit

}

override init(style: UITableViewCell.CellStyle, reuseIdentifier: String!) {
    super.init(style: style, reuseIdentifier: reuseIdentifier)
}

required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
}

}

Next I create the cells, I am showing more so that you get the idea of how I am setting the data for each cell to the selected currency.

Then I add a textFieldDidChange listener:

   override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    var coinName = String()
    tableView.separatorStyle = .none

    let cell:PageCell = tableView.dequeueReusableCell(withIdentifier: "PageCell") as! PageCell
    cell.configureCustomCell()
    let index = indexPath.row
    let coins = Manager.shared.coins
    let coin = coins[index]
    var coinIndex = Int()
    coinIndex = CGPrices.shared.coinData.index(where: { $0.id == coin })!
    let unit = CGExchange.shared.exchangeData[0].rates[defaultCurrency]!.unit
    coinIndexes.append(coinIndex)

    //Prices from btc Exchange rate.
    let btcPrice = CGPrices.shared.coinData[coinIndex].current_price!
    let dcExchangeRate = CGExchange.shared.exchangeData[0].rates[defaultCurrency]!.value
    let realPrice = (btcPrice*dcExchangeRate)

    setBackground(dataIndex: coinIndex, contentView: cell.contentView)

    coinName = CGPrices.shared.coinData[coinIndex].name

    let imageString = CGPrices.shared.coinData[coinIndex].image 
    cell.theImageView.sd_setImage(with: URL(string: imageString), placeholderImage: UIImage(named: "CryptiXJustX"))

    cell.cellTextLabel.text = coinName
    cell.cellDetailLabel.text = "\(unit)\((round(1000*realPrice)/1000))"

    cell.cellCalcInput.addTarget(self, action: #selector(textFieldDidChange(_:)), for: .editingChanged)

// here is the text listener

    return cell
}

@objc func textFieldDidChange(_ textField: UITextField) {

    var index = Int()
    index = textField.tag

    if textField.text != "" {
    calculations(dataIndex: index, calcInput: textField)
    } else {
        print("no text")
    }

}

and here is where I do the calculation when it is typed, and get the results, it is not complete but I need to now somehow get these results shown inside the UITextfield for each cell, relating to the correct currency.

    var coinIndexes = [Int]()
var answers = [Double]()
//
var comparitorIndex = 0
func calculations(dataIndex: Int, calcInput: UITextField) {
    let exchangeRate = CGExchange.shared.exchangeData[0].rates[defaultCurrency]!.value
//
    let btcPrice = CGPrices.shared.coinData[dataIndex].current_price!

//
    if answers.count < coinIndexes.count {

        var calculation = ""
        if CGPrices.shared.coinData[dataIndex].id == "bitcoin" {
            calculation = String(Double(calcInput.text!)! / btcPrice)
        } else {
        calculation = String(Double(calcInput.text!)! * btcPrice)
        }
        let calcAsDouble = Double(calculation)
        let calcFinal = Double(round(1000*calcAsDouble!)/1000)

        var comparitor = coinIndexes[comparitorIndex]
        var comparitorPrice = CGPrices.shared.coinData[comparitor].current_price!

        var comparitorAnswer = (calcFinal/comparitorPrice)
        answers.append(comparitorAnswer)

        comparitorIndex += 1
        print(comparitorAnswer)
        calculations(dataIndex: dataIndex, calcInput: calcInput)
    }
    comparitorIndex = 0

}

Here basically I do the calculations based on which cell is being typed and I can find out which currency it is from the tag, and then using the index of the currency I can check my API and get its name and values, then I do the calculation to compare the other currencies to the value that the user entered. The calculations work and give the correct results, I just don't know how to send the results back into the correct cells. Thank you.

Sorry if it is very sloppy work I am still very new to coding.

Answer 1

You can put your results in a dictionary type [Int : Double] where Int is the coinIndex , and Double part is the answer from the conversion. Then, after your calculations finish, you can call tableView.reloadData.() .

You also need to make modifications to your cellForRowAt to show the conversion.

Try this:

In your UIViewController, declare

var conversions: [Int : Double] = [:]

Then in cellForRowAt :

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    // your code here
    let conversion = conversions[index]
    // the ?? operator will pass "No Value" string if conversion is nil.
    cell.cellCalcInput.text = String(conversion ?? "No Value")
}

You need to update the conversions in your calculation function

func calculations(dataIndex: Int, calcInput: UITextField) {
    // your code here
    conversions[comparatorIndex] = comparatorAnswer
    // once all conversions are entered
    tableView.reloadData()
}

I think you can improve your calculations function. You can iterate on the coin index instead of updating the answers recursively. Good luck!