ios 如何使用 Swift 在文本字段（从右到左）上输入货币格式？

How to input currency format on a text field (from right to left) using Swift?

提问by Bolo

I have a number let's say 0.00.

我有一个数字让我们说0.00。

• When the user taps 1. We should have 0.01
• When the user taps 2. We should display 0.12
• When the user taps 3. We should display 1.23
• When the user taps 4. We should display 12.34

• 当用户点击 1. 我们应该有 0.01
• 当用户点击 2. 我们应该显示 0.12
• 当用户点击 3. 我们应该显示 1.23
• 当用户点击 4. 我们应该显示 12.34

How can I do that with Swift?

我怎样才能用 Swift 做到这一点？

回答by W?odzimierz Wo?niak

For Swift 3. Input currency format on a text field (from right to left)

对于Swift 3。在文本字段上输入货币格式（从右到左）

override func viewDidLoad() {
    super.viewDidLoad()

    textField.addTarget(self, action: #selector(myTextFieldDidChange), for: .editingChanged)
}

func myTextFieldDidChange(_ textField: UITextField) {

    if let amountString = textField.text?.currencyInputFormatting() {
        textField.text = amountString
    }
}

extension String {

    // formatting text for currency textField
    func currencyInputFormatting() -> String {

        var number: NSNumber!
        let formatter = NumberFormatter()
        formatter.numberStyle = .currencyAccounting
        formatter.currencySymbol = "$"
        formatter.maximumFractionDigits = 2
        formatter.minimumFractionDigits = 2

        var amountWithPrefix = self

        // remove from String: "$", ".", ","
        let regex = try! NSRegularExpression(pattern: "[^0-9]", options: .caseInsensitive)
        amountWithPrefix = regex.stringByReplacingMatches(in: amountWithPrefix, options: NSRegularExpression.MatchingOptions(rawValue: 0), range: NSMakeRange(0, self.characters.count), withTemplate: "")

        let double = (amountWithPrefix as NSString).doubleValue
        number = NSNumber(value: (double / 100))

        // if first number is 0 or all numbers were deleted
        guard number != 0 as NSNumber else {
            return ""
        }

        return formatter.string(from: number)!
    }
}

回答by Leo Dabus

You can create a currency text field subclassing UITextField. Add a target for UIControlEvents .editingChanged. Add a selector method to filter the digits from your textfield string. After filtering all non digits from your string you can format again your number using NumberFormatter as follow:

您可以创建一个子类化 UITextField 的货币文本字段。为 UIControlEvents .editingChanged 添加一个目标。添加一个选择器方法来过滤文本字段字符串中的数字。从字符串中过滤掉所有非数字后，您可以使用 NumberFormatter 再次格式化您的数字，如下所示：

Xcode 11 ? Swift 5.1 or later

Xcode 11？Swift 5.1 或更高版本

import UIKit

class CurrencyField: UITextField {
    var decimal: Decimal { string.decimal / pow(10, Formatter.currency.maximumFractionDigits) }
    var maximum: Decimal = 999_999_999.99
    private var lastValue: String?
    var locale: Locale = .current {
        didSet {
            Formatter.currency.locale = locale
            sendActions(for: .editingChanged)
        }
    }
    override func willMove(toSuperview newSuperview: UIView?) {
        // you can make it a fixed locale currency if needed
        // self.locale = Locale(identifier: "pt_BR") // or "en_US", "fr_FR", etc
        Formatter.currency.locale = locale
        addTarget(self, action: #selector(editingChanged), for: .editingChanged)
        keyboardType = .numberPad
        textAlignment = .right
        sendActions(for: .editingChanged)
    }
    override func deleteBackward() {
        text = string.digits.dropLast().string
        // manually send the editingChanged event
        sendActions(for: .editingChanged)
    }
    @objc func editingChanged() {
        guard decimal <= maximum else {
            text = lastValue
            return
        }
        text = decimal.currency
        lastValue = text
    }
}

---

---

extension CurrencyField {
    var doubleValue: Double { (decimal as NSDecimalNumber).doubleValue }
}

---

---

extension UITextField {
     var string: String { text ?? "" }
}

---

---

extension NumberFormatter {
    convenience init(numberStyle: Style) {
        self.init()
        self.numberStyle = numberStyle
    }
}

---

---

private extension Formatter {
    static let currency: NumberFormatter = .init(numberStyle: .currency)
}

---

---

extension StringProtocol where Self: RangeReplaceableCollection {
    var digits: Self { filter { 
extension String {
    var decimal: Decimal { Decimal(string: digits) ?? 0 }
}
.isWholeNumber } }
}

---

---

extension Decimal {
    var currency: String { Formatter.currency.string(for: self) ?? "" }
}

---

---

extension LosslessStringConvertible {
    var string: String { .init(self) }
}

---

---

class ViewController: UIViewController {

    @IBOutlet weak var currencyField: CurrencyField!
    override func viewDidLoad() {
        super.viewDidLoad()
        currencyField.addTarget(self, action: #selector(currencyFieldChanged), for: .editingChanged)
        currencyField.locale = Locale(identifier: "pt_BR") // or "en_US", "fr_FR", etc
    }
    @objc func currencyFieldChanged() {
        print("currencyField:",currencyField.text!)
        print("decimal:", currencyField.decimal)
        print("doubleValue:",(currencyField.decimal as NSDecimalNumber).doubleValue, terminator: "\n\n")
    }
}

---

---

View Controller

视图控制器

class CurrencyTextField: UITextField {

    /// The numbers that have been entered in the text field
    private var enteredNumbers = ""

    private var didBackspace = false

    var locale: Locale = .current

    override init(frame: CGRect) {
        super.init(frame: frame)
        commonInit()
    }

    required init?(coder: NSCoder) {
        super.init(coder: coder)
        commonInit()
    }

    private func commonInit() {
        addTarget(self, action: #selector(editingChanged), for: .editingChanged)
    }

    override func deleteBackward() {
        enteredNumbers = String(enteredNumbers.dropLast())
        text = enteredNumbers.asCurrency(locale: locale)
        // Call super so that the .editingChanged event gets fired, but we need to handle it differently, so we set the `didBackspace` flag first
        didBackspace = true
        super.deleteBackward()
    }

    @objc func editingChanged() {
        defer {
            didBackspace = false
            text = enteredNumbers.asCurrency(locale: locale)
        }

        guard didBackspace == false else { return }

        if let lastEnteredCharacter = text?.last, lastEnteredCharacter.isNumber {
            enteredNumbers.append(lastEnteredCharacter)
        }
    }
}

private extension Formatter {
    static let currency: NumberFormatter = {
        let formatter = NumberFormatter()
        formatter.numberStyle = .currency
        return formatter
    }()
}

private extension String {
    func asCurrency(locale: Locale) -> String? {
        Formatter.currency.locale = locale
        if self.isEmpty {
            return Formatter.currency.string(from: NSNumber(value: 0))
        } else {
            return Formatter.currency.string(from: NSNumber(value: (Double(self) ?? 0) / 100))
        }
    }
}

Sample project

示例项目

回答by NSExceptional

I started with Leo Dabus' answer (which didn't work out of the box for me) and in the process of trying to simplify and make it work ended up with this, which I think is pretty lean & clean if I do say so myself

我从 Leo Dabus 的回答开始（这对我来说不是开箱即用的），在试图简化并使其工作的过程中最终得到了这个，如果我这么说的话，我认为它非常简洁和干净我

extension Double {
            var twoDigits: Double {
                let nf = NSNumberFormatter()
                nf.numberStyle = NSNumberFormatterStyle.DecimalStyle
                nf.minimumFractionDigits = 2
                nf.maximumFractionDigits = 2
                return self
            }
    }
    var cleanText:String!
            let number:String = sender.currentTitle as String!
            if(amountDisplay.text != nil)
            {
                cleanText = String(Array(amountDisplay.text!).map{String(
struct DotNum {
  private var fraction:String = ""
  private var intval:String = ""
  init() {}
  mutating func enter(s:String) {
    if count(fraction) < 2 {
      fraction = s + fraction
    } else {
      intval = s + intval
    }
  }
  private var sFract:String {
    if count(fraction) == 0 { return "00" }
    if count(fraction) == 1 { return "0\(fraction)" }
    return fraction
  }
  var stringVal:String {
    if intval == ""  { return "0.\(sFract)" }
    return "\(intval).\(sFract)"
  }
}
var val = DotNum()
val.enter("1")
val.stringVal
val.enter("2")
val.stringVal
val.enter("3")
val.stringVal
val.enter("4")
val.stringVal
)}.filter{ 
@IBOutlet weak var txtAmount: UITextField!

//MARK: - UITextField Delegate -
    func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool{

        if string.characters.count == 0 {
            return true
        }

        let userEnteredString = textField.text ?? ""
        var newString = (userEnteredString as NSString).stringByReplacingCharactersInRange(range, withString: string) as NSString
        newString = newString.stringByReplacingOccurrencesOfString(".", withString: "")

        let centAmount : NSInteger = newString.integerValue
        let amount = (Double(centAmount) / 100.0)

        if newString.length < 16 {
            let str = String(format: "%0.2f", arguments: [amount])
            txtAmount.text = str
        }

        return false //return false for exact out put
    }
.toInt() != nil }.map{Character(
#!/usr/bin/swift

struct DotNum {
    private var fraction:String = ""
    private var intval:String = ""
    init() {}
    mutating func enter(_ s:String) {
        if fraction.count < 2 {
          fraction = s + fraction
        } else {
          intval = s + intval
        }
    }
    private var sFract:String {
        if fraction.count == 0 { return "00" }
        if fraction.count == 1 { return "0\(fraction)" }
        return fraction
    }
    var stringVal:String {
        if intval == ""  { return "0.\(sFract)" }
        return "\(intval).\(sFract)"
    }
}

var val = DotNum()
val.enter("1")
print(val.stringVal)
val.enter("2")
print(val.stringVal)
val.enter("3")
print(val.stringVal)
val.enter("4")
print(val.stringVal)
)} ) as String
                cleanText = cleanText + number
            }else{
                cleanText = number
            }

            amount = (Double(cleanText.toInt()!) / 100).twoDigits
            formatter.locale = NSLocale(localeIdentifier: currencies[current_currency_index])
            amountDisplay.text = "\(formatter.stringFromNumber(amount!)!)"

回答by Bolo

My final code thanks for your help

我的最终代码感谢您的帮助

$ chmod +x dotnum.swift
$ ./dotnum.swift
0.01
0.21
3.21
43.21

回答by qwerty_so

Try this piece of code:

试试这段代码：

##代码##

回答by Hardik Thakkar

Here is a code for swift 2

这是 swift 2 的代码

##代码##

Note : Connect delegate for textField from storyboard or programatically

注意：从故事板或以编程方式连接 textField 的委托

回答by ziya

Just for fun: copied Thomas's answer(full credits -and points- to him please) into a file to run as a Swift 4.1 script (with minor fixes):

只是为了好玩：将Thomas 的答案（完整的学分 - 并指向他）复制到一个文件中，以作为 Swift 4.1 脚本运行（带有小修复）：

dotnum.swift:

dotnum.swift：

##代码##

Then run it in a terminal:

然后在终端中运行它：

##代码##