Ask HN: Open-source native mobile app analytics solution?

It seems that mobile analytics solutions abound: MixPanel, TestFlight, Flurry, KeenIO, Google Analytics, etc. but as far as I can tell they are all proprietary cloud solutions with their own visualization frontend, etc.

We're currently using Google Analytics for our iOS and Android applications but I dislike having that data locked into Google's servers and the limitations that imposes on what we're able to log.

I'd like to be able to send analytics to our own servers so we can integrate with our existing nginx and backend application logs so we can correlate everything together with Splunk.

We're considering rolling our iOS and Android analytics integrations—it's not too difficult—but neither is it super trivial when you're dealing with opportunistically batching logs to reduce network activity, persisting the logs when temporarily offline, automatically detecting view/activity transitions, etc.

Any suggestions for open source SDKs for doing native mobile analytics? It seems like this is so common there must be something out there that I'm just not able to find…