Hello! I am stuck with the following problem: I am...

# kotlin-native

[Federico Torres]

Hello! I am stuck with the following problem: I am implementing NFC logic in kmp, I need to implement the protocol NFCNDEFReaderSessionDelegateProtocol from kotlin code. The problem is that this protocol was translated from OBJ-C to Kotlin like this:

public expect interface NFCNDEFReaderSessionDelegateProtocol : platform.darwin.NSObjectProtocol {
    @kotlin.commonizer.ObjCCallable public open expect fun readerSession(session: platform.CoreNFC.NFCNDEFReaderSession, didDetectTags: kotlin.collections.List<*>): kotlin.Unit { /* compiled code */ }

    @kotlin.commonizer.ObjCCallable public abstract expect fun readerSession(session: platform.CoreNFC.NFCNDEFReaderSession, didDetectNDEFs: kotlin.collections.List<*>): kotlin.Unit

    @kotlin.commonizer.ObjCCallable public abstract expect fun readerSession(session: platform.CoreNFC.NFCNDEFReaderSession, didInvalidateWithError: platform.Foundation.NSError): kotlin.Unit

    @kotlin.commonizer.ObjCCallable public open expect fun readerSessionDidBecomeActive(session: platform.CoreNFC.NFCNDEFReaderSession): kotlin.Unit { /* compiled code */ }
}

Meaning that there are two readerSession methods with the exact same signature, thus I am unable to implement all the abstract methods of this interface from Kotlin code

[Anton Saatze]

I was facing the same issue with the CBCentralManagerDelegate https://developer.apple.com/documentation/corebluetooth/cbcentralmanagerdelegate?language=objc

The workaround I came up with: provide an Interface, that has all your callback Methods and some swiftcode has to implement the interface and calls them.

In your case:

NFCNDEFReaderSessionDelegateProtocolInterface {
// the two you need
fun readerSessionDidDetectTags(session: platform.CoreNFC.NFCNDEFReaderSession, didDetectTags: kotlin.collections.List<*>)
fun readerSessionDidDetectNDEFs(session: platform.CoreNFC.NFCNDEFReaderSession, didDetectTags: kotlin.collections.List<*>)
// for consistency
fun readerSessionDidInvalidateWithError(session: platform.CoreNFC.NFCNDEFReaderSession, didInvalidateWithError: platform.Foundation.NSError)
fun readerSessionDidBecomeActive(session: platform.CoreNFC.NFCNDEFReaderSession)
}

Let your Switftcode inherit these methods and call them when the swift func gets called.
And eventually inject that class which implemented NFCNDEFReaderSessionDelegateProtocolInterface into your shared code.

[Federico Torres]

yeah your solution seems to be the only possible solution here, I wanted to avoid adding code from client side but seems like I don't have any other choice. Thank you Anton

[Anton Saatze]

@Federico Torres https://kotlinlang.slack.com/archives/C3SGXARS6/p1699101675161829?thread_ts=1699101675.161829&cid=C3SGXARS6
I haven't tried but looks promising.

[Anton Saatze]

Resolving conflicts with Objective-C methods

https://kotlinlang.org/docs/whatsnew-eap.html#resolving-conflicts-with-objective-c-methods