Testing local server with MAMP/wordpress on mobile device?

I prefer to use DNS to deal with local development for mobile. This way you can still use the same IP address for all your local sites, but have a different name for each one (NameBasedVirtualHosts)

• In general settings WordPress; Change The WordPress address from
  localhost to the IP address of your desktop pc/mac (URL)
• In the MAMP PRO general tab; Check; via Xip.io (LAN only)and copy that address
• In general settings WordPress Paste the Xip.io addres in Site Address (URL)
• you can acces the mobile devices via;http://localhost.IPAddressOfYourLocalComputer.xip.io

screenshot Wordpress

I've been able to make a LAN + IOS testing scheme work on OS 10.11 without changing Mamp Pro (4.5) default ports, or change the domain settings in WP admin. Here's all the relevant bits:

• In Finder set up root folder inside "sites" folder i.e. ~/sites/MAMP-hosted/yourdomain.com
• Ensure your mac is using a static IP address, launch Mamp Pro and in the General tab, select that static IP for yourdomain.com in the IP address drop down. localhost should remain the default: *
• In the yourdomain.com > Databases tab, select the database for yourdomain.com (localhost doesn't need to be assigned one)
• All remaining General tab settings are default including name resolution, only etc/hosts option checked
• at the bottom, the localhost > document root should point to the "MAMP-hosted" folder, and yourdomain.com > document root should point to the yourdomain.com folder.

then adjust wp-config to look like this:

define('DB_NAME', 'name-of-your-database');/** MySQL database username */define('DB_USER', 'root');/** MySQL database password */define('DB_PASSWORD', 'root');/** MySQL hostname */define('DB_HOST', 'localhost');define( 'WP_SITEURL', 'http://your-static-IP' );define( 'WP_HOME', 'http://your-static-IP' );

http://your-static-IP should bring up the site on any device on your local network, and http://your-static-IP/wp-login for admin access.

If you write to the database (publish posts, etc) with wp-admin in that state you may need to do some post migration clean up with a plugin like Velvet Blue to remove that IP address.

I haven't experimented with this particular scheme and MAMP on-board SSL, however it's not difficult to switch back once the site is ready to migrate to its dedicated host.