The reasoning being different though, back then Apple wasn't sure Objective-C would take off among Mac OS developer crowd, used to Object Pascal and C++, Java support and its high integration with OS APIs was a kind of Plan B.

Objective-C was actually embraced by the community, only Java heads cared about the bridge, and it was eventually killed.

I feel it was a lost opportunity, but what do I know.

> It makes me wonder how they are dealing with memory management when Java objects are being used from Swift

It uses Swift macros to add a `JavaObjectHolder` property to Swift types annotated with `@JavaClass`[0]. `JavaObjectHolder` is a Swift class that takes a global JNI reference to the Java object, and releases it when the holder is destroyed[1].

The result is that a codegen utility emits Swift structs[2] that wrap the JNI values, and the JNI glue code for method invocation is applied at compile-time when the macros are expanded.

[0] https://github.com/swiftlang/swift-java/blob/e7d7a217e37d49b...

[1] https://github.com/swiftlang/swift-java/blob/main/Sources/Ja...

[2] https://github.com/swiftlang/swift-java/blob/main/Sources/Ja...

IIRC, the ObjC/Java bridge was first done at NeXT for WebObjects around 1996... almost thirty years ago!

If Swift were practical to use for Android app development, I would absolutely do so. I enjoy writing Swift more than I do Kotlin by a good measure and not having to wrestle with gradle and proguard would be a nice bonus.

This would happen in about five minutes if a SwiftUI port was included.

Which ironically would be just like Flutter, totally bypassing any native UI.

My gut feeling is both teams probably have a plan for steamrollering the other in the event of anti monopoly measures forcing each to accept the other store. I.e. it is conceivable you could launch the Play Store on iOS and run a significant proportion of Android apps through a compat layer.

Except contrary to iOS, on Android the C and C++ surface is very small, and calling JNI is a huge performance bottleneck.

Anyone that cares about performance on Android has to write the userspace logic directly in Java or Kotlin, and use Android IPC instead of JNI.

Outside of Apple's ecosystem, is anyone using Swift?

Kotlin is growing in all areas, especially backend (being fully embraced by Spring/Spring Boot et al).

Kotlin-Java interoperability is at a completely different level.

It will also be glorious

This [1] is a good place to start!

[1] https://github.com/finagolfin/swift-android-sdk