Creates and returns an mutable ordered set with a given initial capacity.
- iOS 5.0+
- macOS 10.7+
- Mac Catalyst 13.0+
- tvOS 9.0+
- watchOS 2.0+
The initial capacity of the new ordered set.
A mutable ordered set with initial capacity to hold
Mutable ordered sets allocate additional memory as needed, so
num simply establishes the set’s initial capacity.