I have have a look after Ricochet it just uses Tor for clearing metadata. We had in the past prototypes with tor enabled messaging on mobile and it is not work as expected. Always too long to start on iOS (that can't execute in background), but we found a way to make it work much better i hope in some day we will be able to make it work together, but now it is much better to use tor proxy somewhere and point app to it. Not very user friendly.