Many countries use a comma as a decimal separator.
There is a Wikipedia article about this:
Decimal separator - Wikipedia
You can find out in code, what the decimal separator currently is:
NSLocale *currentUsersLocale;
currentUsersLocale = [NSLocale currentLocale];
NSString *decimalSeparator = [currentUsersLocale objectForKey:NSLocaleDecimalSeparator];
Then you would also need two more graphics:
commaHighlighted.png
commaNormal.png
