CODEWITHSUNDEEP
swiftswift-optionals
esbenr
esbenr

Reputation: 1524

Checking if Optional<Int> is nil

Help me understand this weird nil-check.

I have a variable of the type Int? and I need to switch on nil.

This makes sense:
enter image description here
buildFrameId is 3 and not equal to nil

This does not:
enter image description here
buildFrameId is nil and still not equal to nil

How do I check (single line statement) if buildFrameId is equal to nil?

Upvotes: -1

Views: 72

Answers (1)

esbenr
esbenr

Reputation: 1524

While @martin-r led me to the reason for this behaviour, I came up with a solution my self.

The "problem" is that I'm declaring the variable as nested optional:

var buildFrameId: Int??

This is needed in order for the JSONEncoder to actually encode the nil-property as null instead of omitting it.

The solution is to flatten the nested optional - then normal unwrapping works. I used the proposed solution from this article: https://brodigy.medium.com/nested-optionals-in-swift-design-mistake-by-apple-7240ea61edd

Here is the code for a flattening extension:

extension Optional {
    public func flatten<Result>() -> Result?
    where Wrapped == Result?
    {
        return self.flatMap { $0 }
    }
}

enter image description here

enter image description here

It still doesen't feel that well, but it's better than the proposed solutions in the link provided by @roy-rodney. Encode nil value as null with JSONEncoder

  • I don't know why someone down voted the question - I guess it would have been a bit more helpful with a comment on why.

Upvotes: 0

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