title: Validating the email address in UITextField
body: <p>I am trying to put validation in text field containing email address.<br>What is to be added in string "emailRegEx" to limit the user from inserting three dots in email address or what I have to write in method for same.</p>
  
  <pre><code>- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string. 
  </code></pre>
  
  <p>Here is my code: </p>
  
  <pre><code>- (BOOL)EmailValidationL:(NSString *)email
  {
      NSString *emailRegEx =@"(?:[a-z0-9!#$%\\&amp;'*+/=?\\^_`{|}~-]+(?:\\.[a-z0-9!#$%\\&amp;'*+/=?\\^_`{|}"
      @"~-]+)*|\"(?:[\\x01-\\x08\\x0b\\x0c\\x0e-\\x1f\\x21\\x23-\\x5b\\x5d-\\"
      @"x7f]|\\\\[\\x01-\\x09\\x0b\\x0c\\x0e-\\x7f])*\")@(?:(?:[a-z0-9](?:[a-"
      @"z0-9-]*[a-z0-9])?\\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|\\[(?:(?:25[0-5"
      @"]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-"
      @"9][0-9]?|[a-z0-9-]*[a-z0-9]:(?:[\\x01-\\x08\\x0b\\x0c\\x0e-\\x1f\\x21"
      @"-\\x5a\\x53-\\x7f]|\\\\[\\x01-\\x09\\x0b\\x0c\\x0e-\\x7f])+)\\])";
  
      NSPredicate *regExPredicate =
      [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailRegEx];
      a= [regExPredicate evaluateWithObject:email];
      return a;
  }
  </code></pre>