iOS browser apps are required to use WebKit, but you can pretty heavily modify things. There is a Tor browser app available, it runs Privoxy internally and prox

iOS browser apps are required to use WebKit, but you can pretty heavily modify things. There is a Tor browser app available, it runs Privoxy internally and proxies all traffic from that WebKit instance. Just one since I'm guessing nobody else could be bothered? Edit: you also can't control tracking to the same extent the forked Firefox that Tor uses can.