Return a lowercased copy of the string.
The lowercased method returns a new string with all characters converted to their lowercase equivalents. It handles Unicode characters correctly, including locale-sensitive transformations.
The original string is not modified. For locale-aware lowercasing, use lowercased(with:) and pass a specific Locale.
lowercased is commonly used for case-insensitive comparisons or normalizing user input.
let greeting = "Hello, World!"
print(greeting.lowercased()) // "hello, world!"