Why is the ! in Swift called an 'implicitly' rather than 'explicitly' unwrapped optional?

Question

The name of the ! always confuses me: it\'s called an \'implicitly unwrapped optional\'. However, what is implicit about it? Implicit means \"implied though not pla

Answer 1

Normal Optional

var foo : Foo? = Foo()
foo!.doSomething() // explicitly unwrap it and call the method

Implicitly Unwrapped Optional

var foo : Foo! = Foo()
foo.doSomething() // implicitly unwrap it and call the method just like it is not optional

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In both case, you need something to declare an optional (? or !). Implicitly Unwrapped Optional does not add more. But you can omit unwrap operator when use it.