Thanks for the replies everyone :)
What about Objective-C? There has to be a pretty big market for that.
My only doubt: what if Apple for some reason or another collapses, why whould people keep using it?
I like Objective-C. I'm not sure where it is used outside of Mac OS and iOS but it is a very capable language.
Edit:
Is there any type of Apple-app developing you can do for free these days?
Yes. Develop for the Mac.
You can register as an Apple Developer for free and get technical resources, tools, and information for developing with iOS, Mac OS X and Safari. You need to join a program to distribute your app via an app store, however you can distribute your Mac app via other means if required.