How can data be saved and retrieved from UserDefaults in iOS applications?

In iOS, the UserDefaults class is used for saving and retrieving simple data. It allows storing data as key-value pairs.

Example of saving and retrieving:

// Saving data
let defaults = UserDefaults.standard

defaults.set("Ivan", forKey: "username")
defaults.set(25, forKey: "age")

// Retrieving data
let username = defaults.string(forKey: "username") ?? ""
let age = defaults.integer(forKey: "age")

print("User: \(username), age: \(age)")

It is important to remember that UserDefaults is suitable for small amounts of data, such as settings or simple parameters. For larger or more complex data, it is better to use databases or files.