To determine your IP address you can view it in System Preferences -> Network and select Ethernet or Wireless depending on your configuration. The connected interfaces will have a green dot indicating a connected status.
Alternatively, if you are good comfortable with Terminal Application you can try the following:
Make sure the IP address you are connecting to is correct by going to the MAMP server and running:
ifconfig |grep inet |grep -v inet6
This should give a list of your ip addresses such as
inet 127.0.0.1 netmask 0xff000000
inet 10.0.1.110 netmask 0xffffff00 broadcast 10.0.1.255
With your ipad you will connect, in my case, to "http://10.0.1.110:8888/wordpress/" without the quotes. Do not use the 127.0.0.1 address on your ipad. You look like you may already understand this and were using 192.168.1.7 but it doesn't hurt to double check.
If that doesn't resolve the problem go into "System Preferences" -> "Security"
Select the firewall tab and click "Turn Off Firewall" for the duration of this test. Turn the firewall back on as it protects your computer.
Then try to connect from you iPad again and it should work.
If that does not it may mean the web server is not listening on the correct interface. If the above does not work there are many other paths.
You did turn on your firewall, correct?
