Surely developer productivity and maintainability have increased from the ObjC days, no? Swift criticisms aside, it certainly allows access to more ergonomic high-level coding patterns.
I don’t mind Objective-C when I’m the one writing it and can ensure that the code is responsibly written, but it wasn’t unusual to have to work on existing Obj-C codebases littered with untyped data, casts, etc some amount of which was inevitably erroneous and only seemed to work correctly. Chasing down the origin points of data, fixing a laundry list of method selectors, and adding in checks always sucked with the compiler doing little to give you a hand. With Swift, even in codebases with poor hygiene fixing things is easier since the compiler will yell when something’s wrong.
Or was there issue more intrinsic to the design of the language itself?
You’d basically need to implement the Swift compiler in the Objective-C compiler to get similar type safety, but to make it work you would probably need to change various bits of syntax, drop inline intermixture of C and C++, and remove a lot of Obj-C’s dynamism, basically making it a new language. That’s why Swift was created, and in the past Obj-C’s bracketed smalltalk-like syntax had proven unpopular amongst newcoming devs, so they chose a more mainstream syntax instead.