What is EXC_BAD_ACCESS and how does it occur in Objective-C apps?

EXC_BAD_ACCESS occurs when an app accesses invalid or deallocated memory.

This crash happens when a pointer references freed memory or corrupted heap regions. Common causes include over-released objects, dangling pointers, or use-after-free bugs. ARC reduces frequency but does not eliminate it, especially with C pointers or unsafe_unretained references.