Is it possible to create an own obj-C Cocoa Touch framework which can be used by other developers? And furthermore can you protect this framework?
Yes you can create frameworks for use with Cocoa Touch.
However there are these caveats:
I have guides for these things on my site.
1+2 = http://www.drobnik.com/touch/2010/04/universal-static-libraries/
The other links you have to google because this site does not let me post more than one URL.