This is most likely occurring as you are targeting down to iOS 4. You should change it to be

__unsafe_unretained MyClass *weakWeakSelf = weakSelf;


Nested blocks and references to self
I have seen from time to time questions about various OTP schemes and "OTP" (i.e. stream cipher) schemes. The most common OTP troubles appear to be:


How to extend size of previously generated key or how to generate key.
How to get key material securely to the recipient.


In electronic communication or storage encryption OTP appears scheme that is impossible to make work and if it works benefits are not clear. Requirement that the key needs to be the same size than input seems to be unbearable for many of modern use cases for encryption.

Is there any practice where OTP is useful in modern cryptography except:


As a component used on some proofs.
As a example ideal of encryption algorithm.


I.e.: Is it possible to base on OTP and provide the "information theoretic" strength to hashing (apparently not), authentication, etc.
