If you look closely at how that data was collected, what it's actually measuring is whether a binary links against the ObjC runtime library, which will be the case if a binary transitively depends on any ObjC framework, so even if all new frameworks and executables were written in Swift, we would still expect to see the number presented in that post to continue to grow until most or all of the important frameworks using ObjC are rewritten entirely in Swift. I don't think this data is sufficient to say one way or the other to what degree that is occurring.
Fair criticism. I'm not sure why the author didn't try to detect the use of objc_msg functions, for example. So the ObjC binaries may be overcounted a bit.
Still, the test for Swift binaries seems accurate, and if you look at iOS 13.1 vs 14.0, for example, according to the chart there was an increase of 157 Swift binaries and 446 Objective-C binaries. If we assume there are 157 "false positives" in the ObjC binaries, that's still an increase of 289 ObjC binaries that don't use Swift at all.
D'oh, right. A good test might be difficult. In the absence of that, I guess the safe bet is just to count every Swift binary as a false positive for ObjC, though that's not quite fair, since you can mix the two in the same code base.
