Objective-C Debug Environment Variables

objc-debug-env

OBJC_PRINT_IMAGES               "log image and library names as they are loaded"
OBJC_PRINT_LOAD_METHODS         "log calls to class and category +load methods"
OBJC_PRINT_INITIALIZE_METHODS   "log calls to class +initialize methods"
OBJC_PRINT_RESOLVED_METHODS     "log methods created by +resolveClassMethod: and +resolveInstanceMethod:"
OBJC_PRINT_CLASS_SETUP          "log progress of class and category setup"
OBJC_PRINT_PROTOCOL_SETUP       "log progress of protocol setup"
OBJC_PRINT_IVAR_SETUP           "log processing of non-fragile ivars"
OBJC_PRINT_VTABLE_SETUP         "log processing of class vtables"
OBJC_PRINT_VTABLE_IMAGES        "print vtable images showing overridden methods"
OBJC_PRINT_CACHE_SETUP          "log processing of method caches"
OBJC_PRINT_FUTURE_CLASSES       "log use of future classes for toll-free bridging"
OBJC_PRINT_GC                   "log some GC operations"
OBJC_PRINT_PREOPTIMIZATION      "log preoptimization courtesy of dyld shared cache"
OBJC_PRINT_CXX_CTORS            "log calls to C++ ctors and dtors for instance variables"
OBJC_PRINT_EXCEPTIONS           "log exception handling"
OBJC_PRINT_EXCEPTION_THROW      "log backtrace of every objc_exception_throw"
OBJC_PRINT_ALT_HANDLERS         "log processing of exception alt handlers"
OBJC_PRINT_REPLACED_METHODS     "log methods replaced by category implementations"
OBJC_PRINT_DEPRECATION_WARNINGS "warn about calls to deprecated runtime functions"
OBJC_PRINT_POOL_HIGHWATER       "log high-water marks for autorelease pools"
OBJC_PRINT_CUSTOM_RR            "log classes with un-optimized custom retain/release methods"
OBJC_PRINT_CUSTOM_AWZ           "log classes with un-optimized custom allocWithZone methods"

OBJC_DEBUG_UNLOAD               "warn about poorly-behaving bundles when unloaded"
OBJC_DEBUG_FRAGILE_SUPERCLASSES "warn about subclasses that may have been broken by subsequent changes to superclasses"
OBJC_DEBUG_FINALIZERS           "warn about classes that implement -dealloc but not -finalize"
OBJC_DEBUG_NIL_SYNC             "warn about @synchronized(nil which does no synchronization"
OBJC_DEBUG_NONFRAGILE_IVARS     "capriciously rearrange non-fragile ivars"
OBJC_DEBUG_ALT_HANDLERS         "record more info about bad alt handler use"
OBJC_DEBUG_MISSING_POOLS        "warn about autorelease with no pool in place which may be a leak"

OBJC_USE_INTERNAL_ZONE          "allocate runtime data in a dedicated malloc zone"

OBJC_DISABLE_GC                 "force GC OFF even if the executable wants it on"
OBJC_DISABLE_VTABLES            "disable vtable dispatch"
OBJC_DISABLE_PREOPTIMIZATION    "disable preoptimization courtesy of dyld shared cache"
OBJC_DISABLE_TAGGED_POINTERS    "disable tagged pointer optimization of NSNumber et al."