Restrict NSTextField to only allow numbers

Question

How do I restrict a NSTextfield to allow only numbers/integers? I\'ve found questions like this one, but they didn\'t help!

Answer 1

Here's a solution with filtering. Give a delegate and an outlet to textfield and set controlTextDidChange method.

- (void)controlTextDidChange:(NSNotification *)aNotification {

    NSTextField *textfield = [notification object];
    NSCharacterSet *charSet = [NSCharacterSet characterSetWithCharactersInString:@"0123456789"];

    char *stringResult = malloc([textfield.stringValue length]);
    int cpt=0;
    for (int i = 0; i < [textfield.stringValue length]; i++) {
        unichar c = [textfield.stringValue characterAtIndex:i];
        if ([charSet characterIsMember:c]) {
            stringResult[cpt]=c;
            cpt++;
        }
    }
    stringResult[cpt]='\0';
    textfield.stringValue = [NSString stringWithUTF8String:stringResult];
    free(stringResult);
}

Answer 2

Try to make your own NSNumberFormatter subclass and check the input value in -isPartialStringValid:newEditingString:errorDescription: method.

@interface OnlyIntegerValueFormatter : NSNumberFormatter

@end

@implementation OnlyIntegerValueFormatter

- (BOOL)isPartialStringValid:(NSString*)partialString newEditingString:(NSString**)newString errorDescription:(NSString**)error
{
    if([partialString length] == 0) {
        return YES;
    }

    NSScanner* scanner = [NSScanner scannerWithString:partialString];

    if(!([scanner scanInt:0] && [scanner isAtEnd])) {
        NSBeep();
        return NO;
    }

    return YES;
}

@end

And then set this formatter to your NSTextField:

OnlyIntegerValueFormatter *formatter = [[[OnlyIntegerValueFormatter alloc] init] autorelease];
[textField setFormatter:formatter];

Answer 3

Try this -

NSNumberFormatter *formatter = [[[NSNumberFormatter alloc] init] autorelease];
[formatter setNumberStyle:NSNumberFormatterDecimalStyle];
[textField setFormatter:formatter];