Why Swift reference types are bad for iOS app startup time (opens in new tab)

I'm continually blown away by these small things. During your launch blog post, you showed how configuration tables can add tens of megabytes, and now the Swift<>Obj-C dictionary format can do the same?

It feels like these should be optimizations in Xcode, so its perplexing, but on the flip side, this horrifies me about my JavaScript/Ruby package management. At least on the Xcode side, there is some single party trying to improve.

Interesting read. I've spent a lot of time thinking about ttfb in the browser and have enjoyed exploring the space of web performance "hacks". Obviously people are thinking about measurements like this for mobile apps too, it's just not an area I read about a lot

Great article. Why does the compiler emit Obj-C metadata for non-@objc Swift types? Is this metadata actually used at runtime?