UITextField's numerical pad: dot instead of comma for float values

Question

I'm using a textField which is filled from a numerical pad.

Trouble is that, with lot of local region formats (all european, for example), UITextField's numerical pad has comma instead dot, so everytime I write a decimal number, UITextField can't recognise the decimal comma and it round number; for example 23,07 become 23.

How can I solve this? I thought to set the textField fixed on USA; is it possible? How?

I read the value using this:

var importo = (importoPrevistoTF.text as NSString).floatValue

Answer 1

Potential duplicate of the SO Answer, use NSNumberFormatter

Example Swift:

let number = NSNumberFormatter().numberFromString(numberString)
if let number = number {
    let floatValue = Float(number)
}

Example (Objective-C):

NSNumber *number = [[NSNumberFormatter new] numberFromString: numberString];
float floatValue = number.floatValue;

Answer 2

Swift 4

extension String {
    static let numberFormatter = NumberFormatter()
    var doubleValue: Double {
        String.numberFormatter.decimalSeparator = "."
        if let result =  String.numberFormatter.number(from: self) {
            return result.doubleValue
        } else {
            String.numberFormatter.decimalSeparator = ","
            if let result = String.numberFormatter.number(from: self) {
                return result.doubleValue
            }
        }
        return 0
    }
}

---

"2.25".doubleValue // 2.25
"2,25".doubleValue // 2.25

---

---

Localized approach using NumberFormatter:

extension NumberFormatter {
    static let shared = NumberFormatter()
}
extension StringProtocol {
    var doubleValue: Double? {
        return NumberFormatter.shared.number(from: String(self))?.doubleValue
    }
}

---

Playground testing

// User device's default settings for current locale (en_US)
NumberFormatter.shared.locale            // en_US (current)
NumberFormatter.shared.numberStyle       // none
NumberFormatter.shared.decimalSeparator  // "."
"2.7".doubleValue  // 2.7
"2,7".doubleValue  // nil
"$2.70".doubleValue  // nil

NumberFormatter.shared.numberStyle  = .currency
"2.7".doubleValue  // nil
"2,7".doubleValue  // nil
"$2.70".doubleValue  // 2.7


NumberFormatter.shared.locale  = Locale(identifier: "pt_BR") // pt_BR (fixed)
"2.7".doubleValue     // nil
"2,7".doubleValue     // nil
"R$2,70".doubleValue  // 2.7

NumberFormatter.shared.numberStyle = .none
"2.7".doubleValue      // nil
"2,7".doubleValue      // 2.7
"R$2,70".doubleValue   // nil

Answer 3

Nobody has really addressed the issue directly.

That is, the decimal separator is a convention for a locale.

iOS supports formatting numbers based on a particular locale.

If you're working purely in a given locale, then everything should work correctly. The keypad should accept numbers with the correct decimal separator.

If you're in most countries in Europe, for example, you'd enter a comma as the decimal separator. Entering a dot in those countries is wrong. Somebody from one of those countries would not do that, because it is the wrong decimal separator. A European user is going to know to use a comma as the decimal separator and you don't have to do anything.

If you are in the US, you'd use a period. Using a comma in the US would be wrong.

The way you should display a decimal number is with a number formatter. When you create a number formatter, it uses the current locale by default.

If you need to convert a string containing a decimal number from one locale to the other, you should use 2 number formatters. Use a formatter in the source locale to convert the string to a float. Then use a formatter with the destination locale to convert the number to a string in the output format.

Simply create one number formatter in the default current locale, and create a second number formatter and set it's locale explicitly to the other locale that you want to use.

Answer 4

It's probably a duplicate of this answer, but since the original is in Objective-C, here's a Swift version:

let label = "23,07"
let formatter = NSNumberFormatter()
let maybeNumber = formatter.numberFromString(label)
if let number = maybeNumber {
    println(number)   // 23.07
}

Answer 5

Swift 3: float or double value for string containing floating point with comma

extension String {
    var floatValue: Float {
        let nf = NumberFormatter()
        nf.decimalSeparator = "."
        if let result = nf.number(from: self) {
            return result.floatValue
        } else {
            nf.decimalSeparator = ","
            if let result = nf.number(from: self) {
                return result.floatValue
            }
        }
        return 0
    }

    var doubleValue:Double {
        let nf = NumberFormatter()
        nf.decimalSeparator = "."
        if let result = nf.number(from: self) {
            return result.doubleValue
        } else {
            nf.decimalSeparator = ","
            if let result = nf.number(from: self) {
                return result.doubleValue
            }
        }
        return 0
    }
}

Example:

"5,456".floatValue //5.456
"5.456".floatValue //5.456
"5,456".doubleValue //5.456
"5.456".doubleValue //5.456

"5,456".doubleValue.rounded() //5
"5,6".doubleValue.rounded() //6

Answer 6

Since NSNumberFormatter was replaced by NumberFormatter in the recent version of Swift, I would have pleasure to share with you an upgraded possible solution:

var numberFormatter: NumberFormatter()
importo = Float(numberFormatter.number(from: importoPrevistoTF.text!)!)

Answer 7

A solution that i've found:

let nf = NumberFormatter()
nf.locale = Locale.current
let numberLocalized = nf.number(from: txtAlcool.text!)

In my case I was testing on xcode and all goes ok, but when testing on device it was crashing. All because in Brazil we use metric system, comma separated decimal ",". With this solution it converts automatically from comma to dot.

Answer 8

Code working with the current version of Swift:

let amount = "8,35"

var counter: Int = 0
var noCommaNumber: String!
for var carattere in (amount) {
    if carattere == "," { carattere = "." }
    if counter != 0 { noCommaNumber = "\(noCommaNumber ?? "\(carattere)")" + "\(carattere)" } else { noCommaNumber = "\(carattere)" } // otherwise first record will always be nil
    counter += 1
}

let importo = Float(noCommaNumber)

Answer 9

Swift 4 solution, without using preferredLanguages I had issues with fr_US and decimalPad

extension String {

     func number(style: NumberFormatter.Style = .decimal) -> NSNumber? {
        return [[Locale.current], Locale.preferredLanguages.map { Locale(identifier: $0) }]
            .flatMap { $0 }
            .map { locale -> NSNumber? in
                let formatter = NumberFormatter()
                formatter.numberStyle = style
                formatter.locale = locale
                return formatter.number(from: self)
        }.filter { $0 != nil }
        .map { $0! }
        .first
    }
}

textfield.text?.number()?.floatValue

Answer 10

You can convert it by using NumberFormatter and filtering the different decimal separators:

func getDoubleFromLocalNumber(input: String) -> Double {
    var value = 0.0
    let numberFormatter = NumberFormatter()
    let decimalFiltered = input.replacingOccurrences(of: "٫|,", with: ".", options: .regularExpression)
    numberFormatter.locale = Locale(identifier: "EN")
    if let amountValue = numberFormatter.number(from: decimalFiltered) {
        value = amountValue.doubleValue
    }
    return value
}

Answer 11

        let number                      =   NSNumberFormatter()
        let locale                      =   NSLocale.currentLocale()
        let decimalCode                 =   locale.objectForKey(NSLocaleDecimalSeparator) as! NSString

        number.decimalSeparator = decimalCode as String
        let result = number.numberFromString(textField.text!)

        let value = NSNumberFormatter.localizedStringFromNumber(result!.floatValue, numberStyle: .DecimalStyle)
        print(value)

Hope, this helps you :)