As you can see below, objects in Objective-C all have an isa field which point to what kinda class it is. Eventually, everything points to NSObject which in turn points to Class. Why does this Class have a isa that points to itself? Perhaps it even makes sense to have this self referencing field for the Class object but then what is the point of Xcode showing that in the watch window? Is Xcode just being super literal here or is there ever a point to showing the isa field for the a Class object?
I’m not being nitty about what Xcode’s watch window does, I am genuinely curious as I suspect this confusion means I am not understanding something.
I suspect this is to do with meta-classes. See here for a fairly thorough explanation of meta classes: What is meta class in objective-c?
In summary, there is an NSObject meta-class which is the only self defining class in objective-c, and all descendents of NSObject (including NSObject itself) will have an isa pointing to this.