Comes with bi- and uni-bindings. I like mine better but I wouldn't have done the auto-removal of observers without Yan Raboviks swizzling magic https://github.com/rabovik/RSSwizzle credits due.
I set a toggle in case you feel that's too dangerous to shut it off - Something I use.
I compared a couple of ways of dealing with that, including writing some of my own and I think Yan does it the best.
When doing my own I had some discussions with James Montgomerie regarding race conditions and dealing with class hierarchies. He had solved with a different way here himself: https://github.com/th-in-gs/THObserversAndBinders
Here's the discussions between us regarding the swizzling magic (that Facebook also does here) https://github.com/th-in-gs/THObserversAndBinders/commit/a4c...
The pull requests leading up to me going with Raboviks library (due to better code and smarter implementation)
Test for infinite loop when deallocating: https://github.com/seivan/SHKeyValueObserverBlocks/pull/5
New test to ensure dealloc of observed objects runs: https://github.com/seivan/SHKeyValueObserverBlocks/pull/2