Yeah, the marketing part is hard. I got some traffic from lists for the first few days but that seems to have mostly tapered off now. To be honest I'm not really quite sure where to go from here, I've posted on Touch Arcade and Reddit, and to friends and what not on Facebook, but that's hardly a wide pool. When you talk about emailing and messaging outlets, what sort of places are you talking about? Marketing has never really been my thing, I prefer coding and art and what not.
I think I should have added achievements and unlockables to mine, as I think those go a long way towards keeping people on board while the high score table gets populated, I was trying to go for mostly a competitive vibe, but I think if the leaderboard isn't already reasonably populated, that doesn't really carry people's interest for very long. Going much more for unlockables and achievements in my next project.
For your iOS port are you folks working in Swift or Objective-C? I decided to be an early adopter of Swift, and so far I'm pretty happy with it. I've always found Objective-C so darn clunky looking.