Explain the concept of first-class functions in the Swift language and their role in programming.

In Swift, functions are first-class objects, which means that functions can:

• Be assigned to variables and constants
• Be passed as arguments to other functions
• Be returned from functions
• Be stored in collections

This allows for more flexible and expressive code, for example, using closures for event handling or behavior configuration.

Example:

func greet(name: String) -> String {
    return "Hello, \(name)!"
}

let greeter: (String) -> String = greet
print(greeter("Alice")) // Outputs: Hello, Alice!

First-class functions facilitate functional programming styles, enable high-level abstractions, and simplify working with asynchronous code.