将maxlength设置为特定的UITextField

Question

i tried to set maxlength to my UITextfield but it also affects my other UITextfield.

i tried to use :

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    // Prevent crashing undo bug – see note below.
    if(range.length + range.location > textField.text.length)
    {
        return NO;
    }

    NSUInteger newLength = [textField.text length] + [string length] - range.length;
    return newLength <= 25;
}

i would like to set maxlength to specific uitextfield only.

Answer 1

First, check the editing textfield. Then check the length of the string

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

    /// always allow other textfields
    if (textField != specificTextfield) {
         return YES;
    }

    /// check max length

    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;
}

Ref: Set UITextField Maximum Length

Answer 2

Add tag to your textfield. and in the delegate shouldChangeCharactersInRange method check whether the textfield corresponds to the particular tag.

#define MAXLENGTH 10

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
if (textField.tag == 1){
    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;
}
return true;
}

Answer 3

It is for swift, Try this

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    let length = ((txtPhoneNumber.text?.count)! - range.length) + string.count
    if length <= 9 {
        return true
    }
    return false
}