UITextField货币格式从左到右

Question

当我输入金额时，我想格式化我的UITextField，在左边有一个$。

到目前为止，我的代码所做的是，当我输入时，让它说$5.65，这就是它的输入方式：$0.05->$0.56->$5.65

我希望它不是从右到左，而是从左到右，这样的东西：$5->$5.->$5.6->$5.65

但我想把它限制在只有两位小数，美元符号在左边，你不能键入任何其他字符(例如：！，@，#，$，%，^，A-Z'(

这就是我目前拥有的：

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
let text: NSString = (textField.text ?? "") as NSString
let finalString = text.replacingCharacters(in: range, with: string)
// 'currency' is a String extension that doews all the number styling
amuTextField.text = finalString.currency
// returning 'false' so that textfield will not be updated here, instead from styling extension
return false
}
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))
return formatter.string(from: number)!
}

Answer 1

您可以使用它来限制.:之后的小数位数

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
guard let oldText = textField.text, let r = Range(range, in: oldText) else {
return true
}
let newText = oldText.replacingCharacters(in: r, with: string)
let isNumeric = newText.isEmpty || (Double(newText) != nil)
let numberOfDots = newText.components(separatedBy: ".").count - 1
let numberOfDecimalDigits: Int
if let dotIndex = newText.firstIndex(of: ".") {
numberOfDecimalDigits = newText.distance(from: dotIndex, to: newText.endIndex) - 1
} else {
numberOfDecimalDigits = 0
}
return isNumeric && numberOfDots <= 1 && numberOfDecimalDigits <= 2
}