Why force unwrapping is required in case of enum and switch?

Question

I have notice weird swift behaviour, because in my opinion colours variable shouldn\'t be force unwrapped in case of switch written below, but without unwrapping compiler sh

Answer 1

This is because you create colours variable like optional type. If you do like this:

var colours: Colours
colours = .Red

you will not have to unwrappe this value

If we look at what the optional type is, we will see that this is enum like:

enum Optional {
    case Some(T)
    case None
}

And it can be Some Type like Int for example or None and in this case it's have nil value.

When you make this:

var colours: Colours!

you directly is indicated by the ! that this is not Colours type but this is the enum ImplicitlyUnwrappedOptional type. At moment of creation it's will be Some if equal it value but with this ! you have that it is enum ImplicitlyUnwrappedOptional and in some next moment it will be the None. That's why you have to use ! in switch:

Your colours value is ImplicitlyUnwrappedOptional type and it may be Colours or nil and you have to directly indicate that this is Colours type in `switch``.