[NSURLCredentialStorage sharedCredentialStorage] 线程安全吗?

is [NSURLCredentialStorage sharedCredentialStorage] thread safe?

当主线程上有 Web 视图控件时,从非主线程上下文(例如串行调度队列?)操作从 [NSURLCredentialStorage sharedCredentialStorage] 获取的对象是否安全?

显然答案是肯定的。

https://forums.developer.apple.com/message/26735#26735