Unfortunately, as I recall, the meaning of weakIvarLayout is different depending on whether the code is compiled for ARC, non-ARC, or non-ARC GC/GC-optional. Un

Unfortunately, as I recall, the meaning of weakIvarLayout is different depending on whether the code is compiled for ARC, non-ARC, or non-ARC GC/GC-optional. Unfortunately I don't remember the specifics off-hand. Also, yes, runtime machine code inspection is a ... possibility ... :) It's not that 'hard', but it's certainly harder than clean metadata, and it means maintaining individual introspection code for all supported architectures.