Cool. But I'm not sure what the value is of putting this on the phone you are targeting, rather than on a computer on the same wifi network (or a VPN). Why not just use fiddler/charles/mitmproxy/burp on your computer? Doesn't the desktop interface lend itself much better to something like proxy debugging?

On another note, if you want this to work on cellphone networks as well as wifi, could you create a local VPN server (I think this is possible with swift), connect to it via the iOS tun API and then use the proxy on its local VPN address?

When I want to intercept iOS traffic, I connect to a VPN with proxy settings to a mitmproxy instance running on the VPN subnet.