How to Configure a Proxy Server on an iPhone or iPad

I've found that when I want a proxy, I'll almost always go full anon and use Tor rather than just a standard proxy**. I have Tor set up on my home server, and it gives me a secondary gateway I can switch to when at home (using the ProxySwitchy extension). For away, I can VPN to my server, and I have 2 VPNs set up, one using the default gateway and one using the Tor gateway. This way I also get the strong encryption of a VPN when travelling and using public cell or wifi networks, and it's only a few quick clicks to turn it on or off on any of my laptops or iOS devices.

** The exception is that the server also uses a reverse-proxy to serve up web services and sites over HTTPS using a specified domain. The router black-holes any requests to the server that aren't either the VPN or over port 443, and the server further jettisons any 443 connection if it doesn't match the domains I'm serving.