Why does NSObject's “isMemberOfClass:class” specify __unsafe_unretained in XCode's autocompletion?

Question

The vague overview is that I\'m writing a method in an NSArray Category that will take a Class and filter an Array down to elements that are member

Answer 1

In the absence of an explicit ownership qualification one is inferred; this is usually __strong but in the case of Class it is __unsafe_unretained. This makes sense as Class objects are immortal and need not be memory managed by your code.

So Xcode is just making the implicit explicit and you do not need to do this yourself.