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kotlinlang

Does anyone know why sometimes K/N extensions compile to Obj-C categories and sometimes they compile to "ExtensionsKt" classes? Examples in thread.

This extension:

```// In NSDateExtensions.kt
fun NSDate.toInstant() = Instant.fromEpochSeconds(timeIntervalSince1970.toLong(), 0)```
requires me to use `NSDateExtensionsKt.toInstant(date)` in Swift:

```__attribute__((objc_subclassing_restricted))
__attribute__((swift_name("NSDateExtensionsKt")))
@interface SharedNSDateExtensionsKt : SharedBase
+ (SharedKotlinx_datetimeInstant *)toInstant:(NSDate *)receiver __attribute__((swift_name("toInstant(_:)")));
@end```
However, this extension:

```// In ByteArrayExtensions.kt
fun ByteArray.md5base64(): String = toByteString().md5().base64()```
let's me call the extension `byteArray.md5base64()` directly:

```@interface SharedKotlinByteArray (Extensions)
- (NSString *)md5base64 __attribute__((swift_name("md5base64()")));
@end```
I would always prefer my extensions end up in an Objective-C `(Extensions)` category, so that I can use the extensions the same way in Swift and Kotlin. It's frustrating to run into a compiler error that the extension doesn't exist, and then have to look up the `shared.h` header only to find that I need to go through the "ExtensionsKt" extension class helper.

This is a small thing, not really important.. but I'm curious if there's something I can do to help force the `(Extensions)` category for K/N code gen.

I looked at the bugs related to this trying to find some documentation or explanation - <https://youtrack.jetbrains.com/issues/KT?q=Extension%20category> - but didn't see anything that jumped out at me.

The documentation about this can be found here:
<https://kotlinlang.org/docs/native-objc-interop.html#extensions-and-category-members|https://kotlinlang.org/docs/native-objc-interop.html#extensions-and-category-members>

The difference in your examples is that `NSDate` is an ObjC type and `ByteArray` is a regular Kotlin type.

Ah, thanks for the link and the response.  I glossed right over that...