title: How can I send OTP(One Time Password) from Firebase
body: <p>I am new to Firebase and I am working on an iOS project in which I want to send OTP(One Time Password) to the email id given by a user.</p>
  
  <p>Can I use below method to include any OTP? Or is there any method/way in firebase so that I can send an email with custom email body.
  <strong>Note: I am not using any web service.</strong></p>
  
  <pre><code>-(void)sendEmailVerificationWithCompletion:
  (nullable FIRSendEmailVerificationCallback)completion
  {
  
  }
  </code></pre>