UItextfield shouldChangeCharactersInRange method backSpace not working

Question

I implement this code but backspace not working until i press delete button in UITextfield I want to do with Backspace delete.

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

    NSCharacterSet *myCharSet = [NSCharacterSet characterSetWithCharactersInString:_demo_str];
    for (int i = 0; i < [string length]; i++) {
         unichar c = [string characterAtIndex:i];
         if ([myCharSet characterIsMember:c]) {
            return YES;
      }
    }
    return NO;
  }

When the backspace key is tapped, `string` will be the empty string so you return `NO` which means the change will be ignored so nothing happens. — rmaddy, Dec 06 '14 at 06:49
Return `YES` if `string` is empty so the deletion is processed. — rmaddy, Dec 06 '14 at 06:51
@rmaddy no i can't do this because i specify some condition in which user can enter particular values only from start range to end range — Mayank Patel, Dec 06 '14 at 06:53

score 0 · Accepted Answer · answered Dec 06 '14 at 07:42

Try this code. this working for me

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

  NSCharacterSet *myCharSet = [NSCharacterSet characterSetWithCharactersInString:_demo_str];
  for (int i = 0; i < [string length]; i++) {
     unichar c = [string characterAtIndex:i];
     if ([myCharSet characterIsMember:c]) {
        return YES;
     }
     else
     {
         return NO;
     }
  }
   return YES;
}

score -1 · Answer 2 · edited Jul 04 '21 at 19:50

-1

use this code:

NSCharacterSet *myCharSet = [NSCharacterSet characterSetWithCharactersInString: _demo_str];
if(range.length > 0){
    
    if( !string || [string isEqualToString:@""] || string.length == 0){
          return YES;
    }
    else{
        for (int i = 0; i < [string length]; i++) {
            unichar c = [string characterAtIndex:i];
            if ([myCharSet characterIsMember:c]) {
                return YES;
            }
        }
    }

     return NO;
}
else{
    for (int i = 0; i < [string length]; i++) {
        unichar c = [string characterAtIndex:i];
        if ([myCharSet characterIsMember:c]) {
            return YES;
        }
    }
      return NO;
}

edited Jul 04 '21 at 19:50

shim

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answered Dec 06 '14 at 07:00

SGDev

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`range.length` will be `1` in conditions other than tapping the backspace key. And the length can be other than `1` when the backspace key is tapped. This answer won't work. – rmaddy Dec 06 '14 at 07:04
can you explain me one condition where it is not work. – SGDev Dec 06 '14 at 07:07
I can give you two. 1) Highlight one character in the text field and tap a letter. `range.length` is `1` but the backspace wasn't tapped. 2) Highlight two or more characters in the text field and tap backspace. `range.length` won't be `1` but the backspace was tapped. – rmaddy Dec 06 '14 at 07:09
In other words, `range.length` has nothing to do with whether the backspace was tapped or not. – rmaddy Dec 06 '14 at 07:11
Read my last two comments. Your change is still wrong. – rmaddy Dec 06 '14 at 07:22
Right @rmaddy range.length not working see my answer it's working for me – Mayank Patel Dec 06 '14 at 07:47
i am agree with you "range.length has nothing to do with whether the backspace was tapped or not".now see my latest code it will work in all cases – SGDev Dec 06 '14 at 07:50
1

Your latest update is still wrong. There is no need to check `range.length` at all. And your overly long `if` statement checking `string` should simply be `if (!string.length)`. – rmaddy Dec 06 '14 at 17:48
@SumitGarg it's not working when value between 1000 to 5000 try it ? – Dec 10 '14 at 04:50
@rmaddy not working when range between 1000 to 5000 i tried it .i accept answer it works when we enter value between 5 to 7 not those range 1000 to 5000 – Dec 10 '14 at 04:54
@rmaddy this answer's not wrong but if value between 5000 to 7000 then it now working because it find the value in string not the range – Dec 10 '14 at 04:55
@iOS You need to ask a new question with the relevant code causing your problem. – rmaddy Dec 10 '14 at 04:55

UItextfield shouldChangeCharactersInRange method backSpace not working

2 Answers2