Trying to limit the number of characters of UITextField in iOS

Question

I have a UITextField in my iOS app where I am already modifying the user's input. I realize now that I need to also make sure that the UITextField can hold a certain number of characters. I am implementing the delegate method as follows:

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

    if([[string stringByTrimmingCharactersInSet:[NSCharacterSet controlCharacterSet]]
        isEqualToString:@""])
        return YES;

    NSString *previousValue = [[[textField.text stringByTrimmingCharactersInSet:[[NSCharacterSet decimalDigitCharacterSet] invertedSet]] stringByReplacingOccurrencesOfString:@"." withString:@""] stringByReplacingOccurrencesOfString:@"," withString:@""];
    string = [string stringByTrimmingCharactersInSet:[[NSCharacterSet decimalDigitCharacterSet] invertedSet]];
    NSString *modifiedValue = [NSString stringWithFormat:@"%@%@", previousValue, string];

    if ([modifiedValue length] == 1) {

        modifiedValue = [NSString stringWithFormat:@"0.0%@", string];

    }

    else if ([modifiedValue length] == 2) {

        modifiedValue = [NSString stringWithFormat:@"0.%@%@", previousValue, string];

    }

    else if ([modifiedValue length] > 2) {

        modifiedValue = [NSString stringWithFormat:@"%@.%@",[modifiedValue substringToIndex: modifiedValue.length-2],[modifiedValue substringFromIndex:modifiedValue.length-2]];

    }


    NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
    [formatter setNumberStyle:NSNumberFormatterCurrencyStyle];
    NSDecimalNumber *decimal = [NSDecimalNumber decimalNumberWithString:modifiedValue];
    modifiedValue = [formatter stringFromNumber:decimal];
    [textField setText:modifiedValue];

    return NO;

}

I am not sure with my code above how to factor in the limitation of 22 characters. Can anyone see what it is I need to do?

Answer 1

try like this,

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
if([textField.text length]<=22)
   return YES;
else
   return NO;
}

OR

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

return (textField.text.length <= 22);
}

Answer 2

This is the solution that works best for me, as the answers above won't allow you delete once you've reached the maximum characters.

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    // allow adding of chars
    if (textField.text.length < MAX_CHARS) {
        return YES;
    }
    // allow deleting
    if (textField.text.length == MAX_CHARS && string.length == 0) {
        return YES;
    }

    return NO;
}

It's not the prettiest solution and could probably be refined to handle additional cases, but this worked well for my needs and thought it may be helpful for someone else.

Answer 3

    if ((string.length == 0) || textField.text.length <= MAX_LIMIT)
        return YES;
    else
        return NO;

This is the solution which i found to be perfect.

Answer 4

Try this:-

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


        print("chars \(textField.text!.characters.count) \( string)")

        if(textField.text!.characters.count > 20 && range.length == 0) {
            print("Please summarize in 20 characters or less")
            return false;
        }

        return true;
}