In this article, I will present use cases which are currently impossible or difficult to implement without message passing. For each of these cases, I have filed radars asking for support in Swift. Since Swift could support many of these use cases with other language features, I encourage you to file duplicate radars for each use case you want to see supported in Swift. That way, even if message passing is not added to Swift, support for these other use cases may be added. There is also a radar requesting message passing, (Open Radar) which I also encourage you to duplicate. If you have any use ceases for message passing not covered in this article, please include them in your radar, and let me know. I'll update this article with links to your use cases.