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;
        }
}

have you tried Regular expression ?? – Vinay Chopra Jan 28 '13 at 08:52 — Vinay Chopra, Jan 28 '13 at 08:52
Best answer: http://stackoverflow.com/a/7541846/1463604 – Nishant Jul 17 '15 at 09:01 — Nishant, Jul 17 '15 at 09:01
**FOR SWIFT**... http://stackoverflow.com/a/26337774/294884 – Fattie Sep 28 '15 at 00:34 — Fattie, Sep 28 '15 at 00:34

score 104 · Accepted Answer · edited Nov 08 '17 at 07:42

104

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.

edited Nov 08 '17 at 07:42

Piyush Sanepara

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answered Jan 28 '13 at 09:13

Mrunal

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It should be `return ![string isEqualToString:filtered];` – Fogh Feb 10 '15 at 07:23
3

@Fogh he is already using the `invertedSet` method so we don't need to include `!` in the return statement. – iSee Apr 30 '15 at 09:55
Thank you. Its Working fine. – ssowri1 Dec 22 '16 at 11:43
Seems a bit excessive to split something up, join it back together and then see if the two match when all you really need to do is count how many components there are after the split. If there's more than one, you already know there are unwanted characters. – Ash Mar 21 '17 at 08:36
Swift version here, let ALLOWED_CHARS = "abcdefghijklmnopqrstuvwxyz0123456789_."; func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool { let set = CharacterSet(charactersIn: ALLOWED_CHARS); let filtered = string .components(separatedBy: set) .joined(separator: ""); return filtered != string; } – Anjum Shrimali Apr 03 '17 at 11:32
@ElegyD, you should **add** Swift 4 version, not replace Swift 3 version with Swift 4. – user28434'mstep Feb 08 '18 at 11:42
What's the hell is going here? 1)`NSCharacterSet` from objective-c in swift while siwft has its own character set class; 2)`inverted` is totally extra - you can just use the opposite condition; 3)conversions string->array->string. Why not to replace your code in the `UITextField`'s delegate method with just one line: `return CharacterSet(charactersIn: string).isSubset(of: allowedCharacterSet)`? It is an example for **Swift 4.2** – Vyachaslav Gerchicov Jan 29 '19 at 09:02

amar · Answer 2 · 2013-01-28T08:33:39.377

4

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>"];

edited Jan 28 '13 at 08:33

answered Jan 28 '13 at 08:27

amar

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Change `symbolCharacterSet` to `ACCEPTABLE_CHARECTERS` and this will work how he wants.... – lnafziger Jan 28 '13 at 08:32

score 3 · Answer 3 · edited Jan 19 '15 at 05:12

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];
}

score 3 · Answer 4 · edited May 23 '17 at 11:47

3

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;

}

edited May 23 '17 at 11:47

Community

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answered Apr 28 '16 at 21:58

Evdzhan Mustafa

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Can i add 'if string == "" {return true}'? – a.u.b Nov 11 '16 at 12:23
@a.u.b I don't think the replacement string can ever be empty, but give it a try – Evdzhan Mustafa Nov 11 '16 at 13:23

score 3 · Answer 5 · answered Aug 08 '18 at 07:10

3

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
}

answered Aug 08 '18 at 07:10

Sunil Targe

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This has a bug in it that the return bool should be == and not !=. Currently it will allow all characters except the restricted. – Micah Montoya Apr 29 '19 at 14:07
This doesn't work for case string == "" (for example clearing input) – Akhrameev Apr 09 '21 at 13:36

score 2 · Answer 6 · answered Apr 21 '17 at 06:48

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)
    }

SachinVsSachin · Answer 7 · 2013-01-28T09:35:09.807

1

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;
}

edited Jan 28 '13 at 09:35

answered Jan 28 '13 at 08:19

SachinVsSachin

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This is wrong - it will only return `YES` if every character in `str` is a character in `customStr`. – Carl Veazey Jan 28 '13 at 08:42

score 1 · Answer 8 · answered Nov 02 '16 at 12:50

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;

score 0 · Answer 9 · answered Mar 04 '19 at 12:20

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)
}

score -1 · Answer 10 · answered Jan 28 '13 at 09:10

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");
    }

This is an extremely roundabout. Regular expressions are built for exactly this kind of thing. — Anthony Mattox, Jul 18 '14 at 13:42

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

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