I want to view each user's username inside the twitter card when they share their username or a message that they've received in my website. but the error I'm getting is that twitter meta tag is not reading the variable contents instead it is treating it as a string.
Here are my meta tags on my website:
<meta property="twitter:card" content="summary">
<meta name="twitter:app:name:googleplay" content="">
<meta name="twitter:app:id:googleplay" content="">
<meta property="twitter:site" content="">
<meta name="twitter:title" content="<?php echo '$username'; ?>">
<meta name="twitter:text:title" content="<?php echo '$username'; ?>">
If you can guide me on what I am doing wrong and how to do what I would like to do.