Decimal point in UIKeyboardTypeDecimalPad can't be used in mathematical calculation

问题

I am using the keyboard type: UIKeyboardTypeDecimalPad for two UITextField objects. When trying to perform an addition, I get different results depending on the current locale:

Case 1: US Format: the decimal point appears as . as expected. If I add 12.3 (text field 1) + 12.3 (text field 2), the answer will be 24.6. That's what I want. But:

Case 2: Egypt Format: the decimal point appears as ,. If I repeat the same calculation the answer will be 24. The decimal portion is ignored. Is there a fix for that?

Note: I used the [textField.text floatValue] method.

回答1:

Because floatValue does non-localized scanning, it expects a "US format".

You can use an NSScanner object for localized scanning of numeric values from a string.

See: String Programming Guide: Scanners

Note the last paragraph:

Localization

A scanner bases some of its scanning behavior on a locale, which specifies a language and conventions for value representations. NSScanner uses only the locale’s definition for the decimal separator (given by the key named NSDecimalSeparator). You can create a scanner with the user’s locale by using localizedScannerWithString:, or set the locale explicitly using setLocale:. If you use a method that doesn’t specify a locale, the scanner assumes the default locale values.

See also: How to do string conversions in Objective-C?

Example:

NSScanner *scanner = [NSScanner localizedScannerWithString:textField.text];
double mynumber;
if([scanner scanDouble: &mynumber]){
  // do something
};

回答2:

You can use:

double number = [[self.myTextField.text stringByReplacingOccurencesOfString:@”,” withString:@”.”] doublevalue];

this is ok for all the languages.

来源：https://stackoverflow.com/questions/11487850/decimal-point-in-uikeyboardtypedecimalpad-cant-be-used-in-mathematical-calculat