How can I restrict special characters in UITextField except dot and underscores?

Question

How can I restrict special characters in a UITextField except dot and underscores?

I have tried the code snippet below, but without luck:

#define ACCEPTABLE_CHARECTERS @" ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_."

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
         NSCharacterSet *acceptedInput = [NSCharacterSet characterSetWithCharactersInString:ACCEPTABLE_CHARECTERS];
        if (![[string componentsSeparatedByCharactersInSet:acceptedInput] count] > 1){
            NSLog(@"not allowed");
            return NO;
        }
        else{
            return YES;
        }
}

Answer 1

Try code block given below, it worked fine for me.

SWIFT 3.0

let ACCEPTABLE_CHARACTERS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_"

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    let cs = NSCharacterSet(charactersIn: ACCEPTABLE_CHARACTERS).inverted
    let filtered = string.components(separatedBy: cs).joined(separator: "")

    return (string == filtered)
}

Objective C

#define ACCEPTABLE_CHARACTERS @" ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_."

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string  {
      NSCharacterSet *cs = [[NSCharacterSet characterSetWithCharactersInString:ACCEPTABLE_CHARACTERS] invertedSet];

      NSString *filtered = [[string componentsSeparatedByCharactersInSet:cs] componentsJoinedByString:@""];

      return [string isEqualToString:filtered];
}

Hope it will work for you as well.

Answer 2

Try this

NSCharacterSet  *set= [NSCharacterSet symbolCharacterSet];
if ([string rangeOfCharacterFromSet:[set invertedSet]].location == NSNotFound) {
    // valid
} else {
    // invalid
}

you can make your own set with

NSCharacterSet  *set= [NSCharacterSet characterSetWithCharactersInString:@"<all your symbols you want to ignore>"];

Answer 3

NSString *Regex = @"[A-Za-z0-9^]*";

NSPredicate *TestResult = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", Regex];

[TestResult evaluateWithObject:@"YourTestString"];

Last return boolean value true/false

In Method

+ (BOOL) validateSpecialCharactor: (NSString *) text {
NSString *Regex = @"[A-Za-z0-9^]*";
NSPredicate *TestResult = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", Regex];
return [TestResult evaluateWithObject:text];
}

Answer 4

Swift 2.2 based on Mrunal's answer :

let notAllowedCharacters = " ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_.";
func textField(
    textField: UITextField,
    shouldChangeCharactersInRange range: NSRange,
    replacementString string: String)
    -> Bool
{
    let set = NSCharacterSet(charactersInString: notAllowedCharacters);
    let inverted = set.invertedSet;

    let filtered = string
        .componentsSeparatedByCharactersInSet(inverted)
        .joinWithSeparator("");
    return filtered == string;

}

Answer 5

---

Swift 3.1 solution

---

let ACCEPTABLE_CHARACTERS = " ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_."
    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        let cs = CharacterSet(charactersIn: ACCEPTABLE_CHARACTERS).inverted
        let filtered: String = (string.components(separatedBy: cs) as NSArray).componentsJoined(by: "")
        return (string == filtered)
    }

Answer 6

This may help you try this.. and let me know please

-(BOOL)isHaveSpecialChar:(NSString*)str{
NSString *customStr = @"~`!@#$%^&*()+=-/;:\"\'{}[]<>^?, ";
NSCharacterSet *alphaSet = [NSCharacterSet characterSetWithCharactersInString:customStr];
BOOL isHaveSpecialChar = [[str stringByTrimmingCharactersInSet:alphaSet] isEqualToString:@""];
return !isHaveSpecialChar;
}

Answer 7

Swift 4

let RISTRICTED_CHARACTERS = "'*=+[]\\|;:'\",<>/?%"

UITextField delegate method:

func textField(_ textField: UITextField, shouldChangeCharactersIn _: NSRange, replacementString string: String) -> Bool {
    let set = CharacterSet(charactersIn: RISTRICTED_CHARACTERS)
    let inverted = set.inverted
    let filtered = string.components(separatedBy: inverted).joined(separator: "")
    return filtered != string
}

Answer 8

func  textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {

    let set = NSCharacterSet(charactersIn: "0123456789")
    let inverted = set.inverted;

    let filtered = string.components(separatedBy: inverted).joined(separator: "")
    return filtered == string;

Answer 9

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    let cs = NSCharacterSet.decimalDigits.inverted
    let filtered = string.components(separatedBy: cs).joined(separator: "")
    return (string == filtered)
}

Answer 10

Try this:

NSString *str = @"___asdf.SHiv._.l.asg.  g.g._ASdgASG_.......asfgads.g.   .._____fdgdsfghsdfgh";

    str= [str stringByReplacingOccurrencesOfString:@"." withString:@""];
    str=[str stringByReplacingOccurrencesOfString:@"_" withString:@""];
    str=[str stringByReplacingOccurrencesOfString:@" " withString:@""];
    str=[str stringByTrimmingCharactersInSet:[NSCharacterSet alphanumericCharacterSet]];

    if ([str isEqualToString:@""]) {
        NSLog(@"valid");
    }
    else {
        NSLog(@"invalid");
    }