NEW! Pre-order my latest book, Testing Swift! >>

< Previous: Copying objects   Next: Mutability >

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!")
}

Get six books for only $150

The Swift Power Pack includes my first six books for one low price, helping you jumpstart a new career in iOS development – check it out!

< Previous: Copying objects   Next: Mutability >
MASTER SWIFT NOW
Buy Practical iOS 12 Buy Pro Swift Buy Swift Design Patterns Buy Practical iOS 11 Buy Swift Coding Challenges Buy Server-Side Swift (Vapor Edition) Buy Server-Side Swift (Kitura Edition) Buy Hacking with macOS Buy Advanced iOS Volume One Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with Swift Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Beyond Code

Was this page useful? Let me know!

Click here to visit the Hacking with Swift store >>