Assigning pointer to pointer in Objective-C

Pointer variable is a variable itself, so it has an address. So &str1 results in the address of the pointer variable, and str1 is an expression that results in whatever the pointer variable is holding - the address of the object it's pointing to.

Assume that:

• the object holding the NSString "one" is at address 0x00000100
• the object holding the NSString "two" is at address 0x00000200

Then your pointers might look something like this:

At initialization:

str1
0xbfffd3c8  +---------------+
          |               |
          |  0x00000100   |
          |    ("one")    |
          +---------------+

str2
0xbfffd3cc  +---------------+
          |               |
          |  0x00000200   |
          |    ("two")    |
          +---------------+

=======================================

After the str1 = str2; assignment:

str1
0xbfffd3c8  +---------------+
          |               |
          |  0x00000200   |
          |    ("two")    |
          +---------------+

str2
0xbfffd3cc  +---------------+
          |               |
          |  0x00000200   |
          |    ("two")    |
          +---------------+

Дополнительная ссылка:
stackoverflow.com/questions/529482/objective-c-pointers