The difference between retain and copy in Object C

A NSString object with an address of 0x1111 with the content @ "XXXXX"
Copy to another nsstring, the address is 0x2222, the content is the same, the new object retain is 1, the old object has not changed
Retain to another nsstring, the same address (set up a pointer, pointer copy), the content of course the same, the object's retain value +1

In other words,retain is a pointer copy, copy is a copy of the content

The difference between retain and copy in Object C