In what ways can PHP developers troubleshoot and resolve issues related to displaying external content within iframes, considering changes in application behavior and security headers like X-Frame-Options?

When displaying external content within iframes, PHP developers can troubleshoot and resolve issues by checking for X-Frame-Options headers set by the external server. If the server restricts framing of its content, developers can use PHP to bypass this restriction by setting the X-Frame-Options header to allow framing on their server's response.

<?php
header("X-Frame-Options: ALLOW-FROM https://example.com");
?>