In Swift, you can get the value of a key in a hash (also known as a dictionary) using the subscript notation, which involves placing the key inside square brackets [] after the name of the hash.
Here's an example:
var students = ["Alice": 18, "Bob": 21, "Charlie": 19]
let aliceAge = students["Alice"] // This will get the value associated with the "Alice" key, which is 18
print("Alice's age is \(aliceAge)") // Output: Alice's age is 18
In this example, we create a hash called students that associates the names of three students with their ages. We then use the subscript notation to get the value associated with the "Alice" key and store it in a constant called aliceAge. Finally, we print out a message that includes Alice's age.