Kotlin Multiplatform Mobile question... I have the...

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[Cdev]

Kotlin Multiplatform Mobile question... I have the following:

inline fun <reified T : Any> jsonToConfig(stringJson: String): T? =
    Json.decodeFromString<T?>(stringJson)

Using Kotlinx Serialization decoding from the string works fine in Kotlin. But in Swift:
let projectConfig: ProjectConfig? = config.jsonToConfig<ProjectConfig>(stringJson: jsonString)
I get the following error: "Cannot explicitly specialize a generic function". Any ideas how I could go about getting this to work?

[Anders]

Swift doesn't support the Kotlin call site specialization syntax e.g. obj.foo<Type1, Type2>(). But most importantly, there is no concept of "generic functions" in Objective-C, only generic classes.

So if you inspect the function signature which Swift imports from Objective-C, you will see it isn't a generic function at all.

like

class FileNameKt {
    class func jsonToConfig(string: String): Any?
}

and I am not sure what will happen when you call it. Undefined behaviour likely.

You will either need to define a non-generic version that calls the generic version, or wrapping the function into a generic class if you do need to have it available in its generic form in ObjC/Swift.

fun jsonToMyConfig(string: String): MyConfig? = jsonToConfig<MyConfig>(string)

or

class Converter<T: Any> {
  fun convert(string: String): T? = jsonToConfig<T>(string)
}

[Cdev]

Thanks for info. I'm trying to get the generic form working but when I tried using your example I get "Cannot use T as reified type parameter. Use a class instead".

[louiscad]

@Cdev What you are trying to do can only be done in Kotlin code. Wrap it so before calling from Swift.

[Cdev]

Makes sense, thanks.