Set UITextField Maximum Length [duplicate]

Solution 1:

This works correctly with backspace and copy & paste:

#define MAXLENGTH 10

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

    NSUInteger oldLength = [textField.text length];
    NSUInteger replacementLength = [string length];
    NSUInteger rangeLength = range.length;

    NSUInteger newLength = oldLength - rangeLength + replacementLength;

    BOOL returnKey = [string rangeOfString: @"\n"].location != NSNotFound;

    return newLength <= MAXLENGTH || returnKey;
}

UPDATE: Updated to accept the return key even when at MAXLENGTH. Thanks Mr Rogers!

Solution 2:

UPDATE

I cannot delete this answer because it is the accepted one, but it was not correct. Here is the correct code, copied from TomA below:

#define MAXLENGTH 10

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

    NSUInteger oldLength = [textField.text length];
    NSUInteger replacementLength = [string length];
    NSUInteger rangeLength = range.length;

    NSUInteger newLength = oldLength - rangeLength + replacementLength;

    BOOL returnKey = [string rangeOfString: @"\n"].location != NSNotFound;

    return newLength <= MAXLENGTH || returnKey;
}

ORIGINAL

I think you mean UITextField. If yes, then there is a simple way.

1. Implement the UITextFieldDelegate protocol
2. Implement the textField:shouldChangeCharactersInRange:replacementString: method.

That method gets called on every character tap or previous character replacement. in this method, you can do something like this:

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    if ([textField.text length] > MAXLENGTH) {
        textField.text = [textField.text substringToIndex:MAXLENGTH-1];
        return NO;
    }
    return YES;
}

Solution 3:

A better function which handles backspaces correctly and limits the characters to the supplied length limit is the following:

#define MAXLENGTH 8

    - (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
    {
        int length = [textField.text length] ;
        if (length >= MAXLENGTH && ![string isEqualToString:@""]) {
            textField.text = [textField.text substringToIndex:MAXLENGTH];
            return NO;
        }
        return YES;
    }

Cheers!

Solution 4:

This code limits the text while also allowing you enter characters or paste anywhere into the text. If the resulting text would be too long it changes the characters in the range and truncates the resulting text to the limit.

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    NSUInteger newLength = [textField.text length] - range.length + [string length];
    if (newLength >= MAXLENGTH) {
        textField.text = [[textField.text stringByReplacingCharactersInRange:range withString:string] substringToIndex:MAXLENGTH];
        return NO;
    }
    return YES;
}