What's the difference between the atomic and nonatomic attributes?

To simplify the entire confusion, let us understand mutex lock.

Mutex lock, as per the name, locks the mutability of the object. So if the object is accessed by a class, no other class can access the same object.

In iOS, `@sychronise` also provides the mutex lock .Now it serves in FIFO mode and ensures the flow is not affected by two classes sharing the same instance. However, if the task is on main thread, avoid accessing object using atomic properties as it may hold your UI and degrade the performance.