How to check text field input at real time?

Question

I am writing validation for my textfield, I found something interesting that whether I can check how many digits I am typing into the textfield at real time. My text field i

Answer 1

-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    NSString * searchStr = [textField.text stringByReplacingCharactersInRange:range withString:string];

//    [textField2 setText:[textField1.text stringByReplacingCharactersInRange:range withString:string]];
    NSLog(@"%@",searchStr);
    return YES;
}