Has Anyone Made Passive Income/Money with Creating Mobile Apps?

I'd like to explore making passive income through creating mobile apps. I'm not sure where to ask so I turned to Steemit! I'd like to learn more about people's experiences with it. I put up a job listing on Upwork, and I've received tons of applicants and am ready to get my feet wet with this.

How many apps do you have on the Android marketplace or Apple store? Did you outsource the work? I'd love to hear more about your experience. I hope this gets to some readers! Thanks :)