Question

I have a simple question and that is how do you check if an email exists

I have seen this code on a recent post:

- (BOOL) NSStringIsValidEmail:(NSString *)checkString{

    BOOL stricterFilter = YES; 
    NSString *stricterFilterString = @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}";
    NSString *laxString = @".+@.+\\.[A-Za-z]{2}[A-Za-z]*";
    NSString *emailRegex = stricterFilter ? stricterFilterString : laxString;
    NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailRegex];
    return [emailTest evaluateWithObject:checkString];
 }

My question is, how do I return an action if the BOOL returns YES or NO with an NSTextField?

Answer 1

Simply have a label and set the text of the label to an appropriate message if the email is correct or not.

You can run your checking routine every time the user types a new character into the text field by implementing the following UITextFieldDelegate protocol method:

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

   NSString *newText = [textField.text stringByAppendingString:string];
   if ([self NSStringIsValidEmail:newText]) {
      statusLabel.text = @"Valid.";
   } else {
      statusLabel.text = @"Not a valid email address.";
   }
   return YES;
}