Q:

is [NSURLCredentialStorage sharedCredentialStorage] thread safe?

Is it safe to manipulate the object obtained from [NSURLCredentialStorage sharedCredentialStorage] from a non-main thread context (E.G. a serial dispatch queue?) when there's a web view control on the main thread?

A:

Apparently the answer is yes.
https://forums.developer.apple.com/message/26735#26735

