在Objective-C中将货币字符串转换为浮点数

Question

My goal is simple, I have a textfield storing a localized currency value ($1,000.00 for instance) and I need to get that value back from the textfield as a float to perform some test on the textfield.

The code is really simple, first I format the NSNumber to a localizedString as so :

NSNumberFormatter* formatter = [[NSNumberFormatter alloc] init];
formatter.locale = [NSLocale currentLocale];
formatter.numberStyle = NSNumberFormatterCurrencyStyle;
textfield.text = [formatter stringFromNumber:number];

Everything works fine, but then I do the opposite to get the doubleValue from this localized string :

NSNumberFormatter* formatter = [[NSNumberFormatter alloc] init];
formatter.locale = [NSLocale currentLocale];
formatter.numberStyle = NSNumberFormatterCurrencyStyle; //also tested with NSNumberFormatterDecimalStyle

double d = [formatter numberFromString:textfield.text].doubleValue;

The problem is that the formatter only returns the integer value of my string and not the decimals, worse, if it is a canadian localizedstring (20 000,00 $) it only returns 20.

I've been searching for some time now and can't find anything about this behavior. The workaround is of course storing the NSNumber right before formating it to the textfield and then testing this nsnumber, but I really don't find it pretty.

Answer 1

In Swift, you can do this by similarly setting the locale to the format of the currency, and then getting the double:

    var locale = NSLocale.currentLocale()
    var formatter = NSNumberFormatter()
    formatter.locale = NSLocale(localeIdentifier: "en_US")
    formatter.numberStyle = NSNumberFormatterStyle.CurrencyStyle

    var moneyDouble = formatter.numberFromString(textField.text)?.doubleValue

Answer 2

正如朱塞佩所指出的那样，答案非常简单，我正在抨击我的头靠在墙上，因为没有考虑它。

double d = [NSDecimalNumber decimalNumberWithString:textfield.text locale:[NSLocale currentLocale]].doubleValue;

Answer 3

A slight enhancement to zavtra's answer that returns a float and doesn't force the locale identifier to be en_US (Swift 2):

func floatFromTextFieldText() -> Float {
    let formatter = NSNumberFormatter()
    formatter.locale = NSLocale.currentLocale()
    formatter.numberStyle = NSNumberFormatterStyle.CurrencyStyle
    guard let amount = self.text else { return 0.0 }
    return formatter.numberFromString(amount)!.floatValue
}