Surely if you're using core Swift, or core Objective-C, the runtime is a shared lib shipped with the OS? I can't imagine that every single app built on Swift or Objective-C is bundling the exact same foundation? That seems so unlike Apple to miss such a massive optimization to reduce the download size of nearly every app. I can understand there being exceptions with some apps that use custom setups, but surely the majority of apps are written in XCode using exactly what is provided as a toolset.