Restrict NSTextField input to numeric only? NSNumberformatter

Question

I\'m just getting started up with Mac App Development and so far everything is good well, I\'m just having problems trying to get a NSTextField to only accept numbers for th

Answer 1

Here are the steps to create the same:

Just create the ANYCLASS (called SAMPLE) subclassing the NSNumberFormatter, and in the .m file write the following code...

-(BOOL)isPartialStringValid:(NSString *)partialString newEditingString:(NSString **)newString errorDescription:(NSString **) error {
    // Make sure we clear newString and error to ensure old values aren't being used
    if (newString) { *newString = nil;}
    if (error)     {*error = nil;}

    static NSCharacterSet *nonDecimalCharacters = nil;
    if (nonDecimalCharacters == nil) {
        nonDecimalCharacters = [[NSCharacterSet decimalDigitCharacterSet] invertedSet] ;
    }

    if ([partialString length] == 0) {
        return YES; // The empty string is okay (the user might just be deleting everything and starting over)
    } else if ([partialString rangeOfCharacterFromSet:nonDecimalCharacters].location != NSNotFound) {
        return NO; // Non-decimal characters aren't cool!
    }

    return YES;
}

Now in your Actual Class set the formatter to your NSTextField object like this:

NSTextField *mySampleTxtFld;

And for this set the Formatter:

SAMPLE* formatter=[[SAMPLE alloc]init]; // create SAMPLE FORMATTER OBJECT 

self.mySampleTxtFld.delegate=self;
[self.mySampleTxtFld setFormatter:formatter];

You’re done!