Question

is there any common pattern to create singleton objects for each thread?

When I send a sharedInstance message to the singleton class, I expect an instance that is shared only for the currentThread.

Thanks

EDIT: I found this post very useful http://ddeville.me/2011/02/creating-shared-instances-of-non-thread-safe-classes/

Answer 1

A singleton and one object per thread requirement is an contradiction.
You probably want a thread local object. That is one object specific for each thread.

Thread local objects can be implemented by using [NSThread threadDictionary].
There you could store such an object as NSValue which can hold even a pointer.