NSCharacterSet illegalCharacterSet example in Objective C (iOS).

NSCharacterSet illegalCharacterSet

Returns a character set containing values in the category of Non-Characters or that have not yet been defined in version 3.2 of the Unicode standard.

+ (id)illegalCharacterSet

Return Value of [NSCharacterSet illegalCharacterSet]
A character set containing values in the category of Non-Characters or that have not yet been defined in version 3.2 of the Unicode standard.

NSCharacterSet illegalCharacterSet example.

    filename = [[filename componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] componentsJoinedByString:@"" ];
    filename = [[filename componentsSeparatedByCharactersInSet:[NSCharacterSet illegalCharacterSet]] componentsJoinedByString:@"" ];
    filename = [[filename componentsSeparatedByCharactersInSet:[NSCharacterSet symbolCharacterSet]] componentsJoinedByString:@"" ];
    fileURLString = [NSTemporaryDirectory() stringByAppendingPathComponent:filename];
    fileURL = [NSURL URLWithString:fileURLString];

Example of [NSCharacterSet illegalCharacterSet].

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)string{

if (range.location>=70){
    return  NO;
}
else
{
    NSCharacterSet *unacceptedInput = nil;

    if (textView == inputTextSection || range.location>=70)  {

        NSRange uppercaseCharRange;
        uppercaseCharRange = [string rangeOfCharacterFromSet:[NSCharacterSet uppercaseLetterCharacterSet]];

        if (uppercaseCharRange.location != NSNotFound) {

            inputTextSection.text = [inputTextSection.text stringByReplacingCharactersInRange:range
                                                                                   withString:[string lowercaseString]];

            return NO;
        }

        if ([[inputTextSection.text componentsSeparatedByString:@"@"] count] > 1) {
            unacceptedInput = [[NSCharacterSet characterSetWithCharactersInString:[ALPHA_NUMERIC stringByAppendingString:@".-"]] invertedSet];

        } else {
            unacceptedInput = [[NSCharacterSet characterSetWithCharactersInString:[ALPHA_NUMERIC stringByAppendingString:@"\n .,;:<>[]!$%&'*+-/=?^_{}()~@"]] invertedSet];
        }
    }
    else {
        unacceptedInput = [[NSCharacterSet illegalCharacterSet] invertedSet];
    }

    return ([[string componentsSeparatedByCharactersInSet:unacceptedInput] count] <= 1);

    return YES;
    }
}

NSCharacterSet illegalCharacterSet example.

// Define some constants:
#define ALPHA                   @"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
#define NUMERIC                 @"1234567890"
#define ALPHA_NUMERIC           ALPHA NUMERIC

// Make sure you are the text fields 'delegate', then this will get called before text gets changed.
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {

    // This will be the character set of characters I do not want in my text field.  Then if the replacement string contains any of the characters, return NO so that the text does not change.
    NSCharacterSet *unacceptedInput = nil;

    // I have 4 types of textFields in my view, each one needs to deny a specific set of characters:
    if (textField == emailField) {
        //  Validating an email address doesnt work 100% yet, but I am working on it....  The rest work great!
        if ([[textField.text componentsSeparatedByString:@"@"] count] > 1) {
            unacceptedInput = [[NSCharacterSet characterSetWithCharactersInString:[ALPHA_NUMERIC stringByAppendingString:@".-"]] invertedSet];
        } else {
            unacceptedInput = [[NSCharacterSet characterSetWithCharactersInString:[ALPHA_NUMERIC stringByAppendingString:@".!#$%&'*+-/=?^_`{|}~@"]] invertedSet];
        }
    } else if (textField == phoneField) {
        unacceptedInput = [[NSCharacterSet characterSetWithCharactersInString:NUMERIC] invertedSet];
    } else if (textField == fNameField || textField == lNameField) {
        unacceptedInput = [[NSCharacterSet characterSetWithCharactersInString:ALPHA] invertedSet];
    } else {
        unacceptedInput = [[NSCharacterSet illegalCharacterSet] invertedSet];
    }

    // If there are any characters that I do not want in the text field, return NO.
    return ([[string componentsSeparatedByCharactersInSet:unacceptedInput] count] <= 1);
}

End of NSCharacterSet illegalCharacterSet example article.