Is it possible to cast or convert a `NSNumber` Objective-C reference to a Kotlin `Number`? The <docs...

# kotlin-native

[Jeff Lockhart]

Is it possible to cast or convert a NSNumber Objective-C reference to a Kotlin Number? The docs describe casting the other way, but not clear how to accomplish the reverse.

[Jeff Lockhart]

The best I can come up with is something like this:

fun NSNumber.toNumber(): Number {
    return when (CFNumberGetType(this as CFNumberRef)) {
        kCFNumberSInt8Type, kCFNumberSInt16Type, kCFNumberSInt32Type, kCFNumberSInt64Type,
        kCFNumberIntType, kCFNumberCFIndexType, kCFNumberNSIntegerType -> integerValue
        kCFNumberFloat32Type, kCFNumberFloat64Type, kCFNumberFloatType, kCFNumberCGFloatType -> floatValue
        kCFNumberCharType -> charValue
        kCFNumberShortType -> shortValue
        kCFNumberLongType, kCFNumberLongLongType -> longLongValue
        kCFNumberDoubleType -> doubleValue
        else -> longLongValue
    }
}

But it doesn’t like casting NSNumber to CFNumberRef. Says “this cast can never succeed”. Are toll-free bridged type casts supported?

[Artyom Degtyarev [JB]]

I’m afraid this is not a way to make such casts. See this YouTrack issue for some details. Also, please look through the Duplicate section there, something might be relevant for your case.