“oldValue” and “newValue” default parameters names inside willSet / didSet unrecognized

Question

I am currently writing Swift 3 code in Xcode 8.

When using oldValue and newValue default parameters inside the willSet and

Answer 1

The special variable newValue only works within willSet, while oldValue only works within didSet.

The property as referenced by its name (in this example vc) is still bound to the old value within willSet and is bound to the new value within didSet.