Question

I need to create a custom NSFormatter for some fields but in case of a not valid value i don’t want to use an alert sheet to show error message… i prefer use only a NSBeep(). Is this possible or i have to present the error with the standard sheet proposed by NSFormatter ?

Answer 1

In your NSFormatter subclass implementation you should be able to do something like:

@implementation MyFormatter

- (BOOL)isPartialStringValid:(NSString *)partialString
            newEditingString:(NSString **)newString
            errorDescription:(NSString **)error
{
    // Test if the string is too long, for example 5 characters
    if ([partialString length] > 5)
    {
        NSBeep();
        return NO;
    }

    // other tests here

    *newString = partialString;

    return YES;
}

@end