Validating a text field with a special character

Question

In my application. I want to check a text box with special characters,

Ex. if the user clicks a button? from the keyboard, what the user can not enter? in the text box

Please suggest how can I do this?

Answer 1

Try as below, this will help you. It will only accept letters

   - (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
    {
        //For avoiding user to enter non digital number..
        if([[string stringByTrimmingCharactersInSet:[[NSCharacterSet letterCharacterSet] invertedSet]] isEqualToString:@""])
        {
            return NO;
        }
        else
        {
            return YES;
        }
    }

Answer 2

check this

use

- (BOOL) textField:(UITextField*)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString*)textEntered

Answer 3

, :

    -(NSString *) formatIdentificationNumber:(NSString *)string
     {
       NSCharacterSet * invalidNumberSet = [NSCharacterSet characterSetWithCharactersInString:@"\n_!@#$%^&*()[]{}'\".,<>:;|\\/?+=\t~` "];

    NSString  * result  = @"";
    NSScanner * scanner = [NSScanner scannerWithString:string];
    NSString  * scannerResult;

    [scanner setCharactersToBeSkipped:nil];

     while (![scanner isAtEnd])
     {
    if([scanner scanUpToCharactersFromSet:invalidNumberSet intoString:&scannerResult])
    {
        result = [result stringByAppendingString:scannerResult];
    }
    else
    {
        if(![scanner isAtEnd])
        {
            [scanner setScanLocation:[scanner scanLocation]+1];
        }
    }
 }

  return result;
  }