Location

https://docs.swift.org/swift-book/documentation/the-swift-programming-language/thebasics#Force-Unwrapping

Description

The line says:

When nil represents an unrecoverable failure, such as a programmer error or corrupted state, you can access the underlying value by adding an exclamation mark (!) to the end of the optional’s name.

There is no meaning of accessing underlying value without specifying its for the optional and not the nil value itself.

Correction

When nil represents an unrecoverable failure, such as a programmer error or corrupted state, you can access the underlying value of the optional by adding an exclamation mark (!) to the end of the optional’s name.