What are Zombie objects in Objective-C debugging?

Updated May 17, 2026

Short answer

Zombie objects are deallocated objects replaced with debug placeholders to catch invalid access.

Deep explanation

When Zombies are enabled, deallocated objects are not freed but converted into NSZombie instances. Any message sent to them triggers a descriptive crash instead of silent memory corruption, making debugging EXC_BAD_ACCESS significantly easier.

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