Bindings read values from objects.
Sometimes, a value will need some massaging before it can be used.
To fulfill this purpose, Apple created NSValueTransformer.
One example is
NSNegateBoolean, which transforms
The Hidden binding on views in Interface Builder
is very convenient, as long as you are binding to a Bool that is
when you want the view hidden.
If your Bool is
true for shown,
you can simply enter
NSNegateBoolean in the
Value Transformer field of the bindings inspector.
No need to jump through hoops to create a bindings-compliant Bool for the
You can create your own NSValueTransformer subclasses and attach them to bindings in your ...