Deinitializers

The fourth difference between classes and structs is that classes can have deinitializers – code that gets run when an instance of a class is destroyed.

To demonstrate this, here’s a Person class with a name property, a simple initializer, and a printGreeting() method that prints a message:

class Person {
    var name = "John Doe"

    init() {
        print("\(name) is alive!")
    }

    func printGreeting() {
        print("Hello, I'm \(name)")
    }
}

We’re going to create a few instances of the Person class inside a loop, because each time the loop goes around a new person will be created then destroyed:

for _ in 1...3 {
    let person = Person()
    person.printGreeting()
}

And now for the deinitializer. This will be called when the Person instance is being destroyed:

deinit {
    print("\(name) is no more!")
}

SPONSORED Debug 10x faster with Proxyman. Your ultimate tool to capture HTTPs requests/ responses, natively built for iPhone and macOS. You’d be surprised how much you can learn about any system by watching what it does over the network.

Try Now!

Sponsor Hacking with Swift and reach the world's largest Swift community!