How much memory does an NSObject occupy?

aNSObjectHow much memory does an object take up?

Due to the memory allocation mechanism, an NSObject object is allocated 16 bytes of memory.

But in fact, in 64-bit, only 8 bytes are used; In 32 bits, only 4 bytes were used

The size of a member variable of an NSObject instance object is actually 8 bytes

#import <Objc/Runtime>
Class_getInstanceSize([NSObject Class])
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Nature is

size_t class_getInstanceSize(Class cls)
{
    if(! cls)return 0;
    return cls->alignedInstanceSize();
}
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Gets the size of memory pointed to by the Obj -c pointer, which is actually 16 bytes

#import <malloc/malloc.h>
malloc_size((__bridge const void *)obj); 
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Object memory is aligned when allocating memory, so in iOS, memory is allocated in multiples of 16 bytes.

Can through the following url: openSource.apple.com/tarballs to view the source code.

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