What is the time complexity of deleting an element from the middle of a dictionary?

In Swift, a dictionary (Dictionary) is implemented based on a hash table. The operation of removing an element by key has an average time complexity of O(1), meaning it is performed in constant time. This is because the dictionary directly computes the index of the element through a hash function.

However, in the worst case, due to hash collisions, the complexity can increase to O(n), where n is the number of elements in the dictionary. But such cases are rare in practice.

Important: there is no concept of "middle" in a dictionary as in an array, since elements are unordered. Removal occurs by key, not by position.