Which is threadsafe atomic or non atomic?

Question

I searched and found immutable are thread safe while mutable is not. This is fine. But i got misleading notes, blogs, answers about atomic vs non-atomic about thread safety,

Answer 1

atomic guarantees atomic access to the variable but it DOESN'T make your code thread safe. Neither does non-atomic.

With "atomic", the synthesized setter/getter methods will ensure that a whole value is always returned from the getter or set by the setter, regardless of setter activity on any other thread. So if thread A is in the middle of the getter while thread B calls the setter, an actual viable value will be returned to the caller in A. For nonatomic, you have no such guarantees.