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iOS

Posted by Edwin Escobar
Edwin Escobar
4,594 Points

Why isn't it possible to 'switch nil' on Swift?

Why is this posible with if but it isn't with switch?

func addChoice (title: String, page: Page) -> Page {
    if firstChoice == nil {
        firstChoice = (title, page)
    } else if secondChoice == nil {
        secondChoice = (title, page)
    }
    return page
}

func addChoice2 (title: String, page: Page) -> Page {
    switch nil {
    case firstChoice: firstChoice = (title, page)
    case secondChoice: secondChoice = (title, page)
    default: break
    }
    return page
}

2 Answers

Kieran Black
Kieran Black
9,139 Points
Kieran Black
Kieran Black
9,139 Points

Hi Edwin,

nil is a value (well an absence of a value, in the way that black is the absence of colour but classed as a colour), there is no point switching on a value as it will always be the same, it's not variable.

Your switch should be on a variable and the nil should be within a case.

There isn't enough code in your specific case to be able to provide an example on it, for example what is Page and how are ** firstChoice** and ** secondChoice** provided to the function.

Hope that helps.

KB :octopus:

Edwin Escobar
Edwin Escobar
4,594 Points
Edwin Escobar
Edwin Escobar
4,594 Points

Thanks. Well, switch can work with static values as it is written on the documentation, so I don't think thats the problem.

firstChoice and secondChoice are optionals, so they can be nil and it works with the if statement, then I don't see why switch is incapable of taking nil.