When I lost my job 6 months ago, I used that opportunity to become a full time iOS app developer. I executed my original plan and although I saw an increase in app revenue, it's not sufficient to make a living from it. In the first 5 months app sales remained more or less the same (~ 20€/day) although my apps made huge leaps forward in terms of functionality.
Mid march, I started an ad campaign on iPhoneography and spent 2 days doing nothing but contacting bloggers, magazines and photography experts to promote my apps. That resulted in a number of publications and a noticeable increase in app sales.
After a week, the upward trend stopped and sales went down again. The downward trend stabilized when a 30-day ad campaign went live on Digital Photography School. If sales stay stable for 30 days, that will be hardly sufficient to break even on the ad campaign costs. But I'll elaborate on that in a future blog post.
I consider the last 6 months a very valuable investment. I already had 3 years of experience with iOS development in my spare time, but those extra 6 months of full-time iOS development gave me the opportunity to dig deeper in certain areas of iOS.