LICENSE issue
it seems, toxicity cannot distribute under apache license since toxcore (which is part of toxicity) is licensing under GPL. Refer this page for more info: http://www.apache.org/licenses/GPL-compatibility.html
(I really do not like GPL, and I'm very sad toxcore is licensed with GPL).
:(
Unfortunately I have no say on toxcore licensing matters. If there's a way around it I wouldn't know. I'm not too familiar with licensing.
okay, if you are open to new information, here you can find some: Nice and simple site made by github staff. It explains some popular licenses. Direct link for GPLv3 which is used in toxcore. Take a look at section 5.c, it describes that you have to license derivative as GPLv3 also unless you have license exception from toxcore team. GPL on Wikipedia may briefly explain a bit. Check it in your local language. irungentoo/toxcore#58 This huge thread tries to explain why toxcore is licensed under GPL terms.
Also, as far as I know, there is now way to distribute apps with GPL license in the Apple AppStore. The saddest thing! We should discuss this with toxcore team. I think they do not want to lose ios platform.