At the bottom of page 134 we’re told to
“Select the newly added container view and open the Pin menu”
I see that a “Pin Button” is, in effect, defined by a figure on page 128 and since pressing that button brings up a menu, that must be the menu referred to.
Unfortunately, the Xcode interface doesn’t seem to refer to this as a “Pin” button or menu, as far as I can see. Instead, the tool tip I see when I hover my mouse over it is “Add New Constraints”. Searching for “Pin” in the help returns nothing.
If there really is no name Xcode gives this button, perhaps including an image of the button would make more sense
I’m using Version 8.1 (8B62)