Legal Question in Business Law in California

Probably not. (Do you have a contract with them? Read it.) Next time you have an idea don't give it away, take it to a patent lawyer.

The first thing a lawyer would want to review in considering whether to represent you against the application production company is your written contract with them. I can't say that a suit for misappropriation of an idea is unwinnable per se, but without a written agreement that has clearly been breached by the defendant your odds of prevailing aren't good. In particular, unless you have a pretty solid contract with the producer, I think you'd have a hard time finding a competent attorney who'd take the case on a contingent-fee basis.

I'm guessing you don't even have a written contract with them, and if you do it won't support a case against them. There may, however, be other angles to this that would give you a right to sue them for a share of the profits from the apps. If you would like to discuss your situation further, at no charge or obligation, I would be happy to meet with you in my Walnut Creek office.