What is the purpose of the final modifier and in which cases is its use justified?

The final modifier in Swift is used to prevent overriding a class, method, or property in subclasses. If a class is declared as final, it cannot be inherited. If a method or property is marked as final, it cannot be overridden.

Using final is justified in the following cases:

• When you want to ensure that the behavior of a class or method is not changed in subclasses, which increases code safety.
• For performance optimization, as the compiler can better optimize calls to final methods.
• To avoid errors related to incorrect overriding.

Example:

final class NetworkManager {
    func fetchData() {
        // implementation
    }
}

// Attempting to inherit will cause an error
// class CustomNetworkManager: NetworkManager {} // Error

class BaseClass {
    final func doSomething() {
        print("Base method execution")
    }
}

class SubClass: BaseClass {
    // override func doSomething() {} // Error, method is final
}