In xcode does anyone know how to check that a string is this kind of phone number (123) 456-7890?

I've tried this and it's not working:

range1 = NSMakeRange(0,[string length]);
NSRegularExpression *regex;
regex = [NSRegularExpression 
        regularExpressionWithPattern:@"([0-9]{开发者_JS百科3}) [0-9]{3}-[0-9]{4}"
        options:0 error:NULL];
range2 = [regex rangeOfFirstMatchInString:string options:0 range:range1];
if (NSEqualRanges(range1, range2)) {
    return YES;
}

// range2 always equals the "not found" range. // Thx

I think it should be '\\' (double slashes) and not '\' (single slash)..

- (BOOL) validatePhone: (NSString *) candidate {
    NSString *phoneRegex = @"\\(?([0-9]{3})\\)?[-. ]?([0-9]{3})[-. ]?([0-9]{4})";

    NSPredicate *phoneTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", phoneRegex];
    return [phoneTest evaluateWithObject:candidate];
}