Question

I am having trouble understanding the concept between two things being equal and two things being identical. What confuses me is the statement “Two objects can be identical, which means they are equal. But, two object that are equal are not identical.” Could someone please help me understand the difference? Thanks.

Answer 1

in objective-c, slightly pseudo code…

NSString * a = @"hello";
NSString * b = @"hello";

a == a    //they are identical (the same object)
[a isEqualToString:a]; //they are equal.
a != b    //Even though the string contents are the same they are not the same object.
[a isEqualToString:b]; // they aren't identical but they are equal.

For a very long and good blog post on the topic see this

http://www.karlkraft.com/index.php/2008/01/07/equality-vs-identity/