Returns the dictionary object associated with the specified key.
- iOS 2.0+
- macOS 10.0+
- Mac Catalyst 13.0+
- tvOS 9.0+
- watchOS 2.0+
A key in the current user‘s defaults database.
The dictionary object associated with the specified key, or
nil if the key does not exist or its value is not a dictionary.
The returned dictionary and its contents are immutable, even if the values you originally set were mutable.