Silly question, for people with KMM/iOS experience...

# kotlin-native

[Anton Afanasev]

Silly question, for people with KMM/iOS experience here.
What is the best way to switch over kotlin sealed classes on iOS (if at all)?

data class Payload(val name: String)

sealed class Event {
   
    class Inserted(val payload: Payload) : Event()
    
    class Updated(val payload: Payload) : Event()
    
    class UpdatedAll(val payloads: List<Payload>, val flag: Boolean) :
        Event()
}

[Paul Woitaschek]

Write an extension on the event containing 3 lambdas in it's signature

[Anton Afanasev]

Can you give a short example?

[Paul Woitaschek]

fun<t> reduce(event : Event, insert: (Insert)-> T, updated: (Updated) -> T) : T

return when event
is Updated > updated (event)
is Insert > insert(event)

[Paul Woitaschek]

It's not a silly question

[Paul Weber]

switch event {
case is Inserted:
    let inserted = event as! Inserted
    // do something with inserted.payload
default:
    break
}

[Paul Weber]

Would be the way to switch on it in swift.

[Sam]

You should be able to remove the ! by writing

switch event {
case let inserted as Inserted:
    // do something
default:
   break
}

[Paul Weber]

True, that does work. Even better! Thanks.

[Anton Afanasev]

Thanks everyone!

[Paul Woitaschek]

The code I posted is explicitly there to handle the exhaustiveness and omit a default block

[Paul Weber]

And that’s cool and all but sometimes it’s also great to stick with native conventions.

That’s one of the big positives with KMM. Share as much as possible but let the native devs do their thing the way they’re used to.

Also, I think when (SealedClass) still compiles when you omit a case? It’s just a warning otherwise. So you’d still have to check KMM code to be sure it’s exhaustive.

I still liked it. Wouldn’t have thought of that myself. 👍🏼

[Paul Woitaschek]

No, as of 1.6 that's an error