The == operator checks for value-equality in Swift, and for there is no default implementation for it. What you want is reference equality, which you can get using === and !== in Swift.

See the documentation for more details.

Identity Operators

Because classes are reference types, it is possible for multiple constants and variables to refer to the same single instance of a class behind the scenes. (The same is not true for structures and enumerations, because they are always copied when they are assigned to a constant or variable, or passed to a function.)

It can sometimes be useful to find out if two constants or variables refer to exactly the same instance of a class. To enable this, Swift provides two identity operators:

Identical to (===) Not identical to (!==)

Note that for the === operator to work, the objects must conform to the AnyObject protocol. You can guarantee this by suffixing the protocol with ": class", like this:

protocol SomeProtocol : class { ... }

If you want to compare if two Observing point to the same instance, use the === operator instead. This requires that the observer's must conform to AnyObject. An easy way to require Observing to only apply to AnyObjects would be to add the @class_protocol prefix to the protocol declaration.