> IMO allowing interior mutability by default on `let`-bound reference (`class`) types was a mistake in the language design and the same syntax should've been required there, but I assume Apple wanted to make things clearer for programmers who don't have a C/C++/similar background and so don't yet understand the distinction between [stack-allocated, pass-by-copy] values and references [to heap-allocated, reference-counted objects].
They also likely didn't want to make the work of bridging/using Obj-C types (which I believe are all reference types) even harder.
They also likely didn't want to make the work of bridging/using Obj-C types (which I believe are all reference types) even harder.