Uppercase and Lowercase in Swift in Swift

In Swift, String values have built-in methods to change their case:

s.uppercased()   // converts all characters to uppercase
s.lowercased()   // converts all characters to lowercase

Here are some examples:

let word = "Hello World"
let upper = word.uppercased()  // "HELLO WORLD"
let lower = word.lowercased()  // "hello world"

let name = "ALICE"
print(name.lowercased())  // "alice"

These methods return a new String — the original is not modified.