Lazy initialisation and retain cycle

Question

While using lazy initialisers, is there a chance of having retain cycles?

In a blog post and many other places [unowned self] is seen

class Person {      var name: String      lazy var personalizedGreeting: String = {         [unowned self] in         return "Hello, \(self.name)!"         }()      init(name: String) {         self.name = name     } } 

I tried this

class Person {      var name: String      lazy var personalizedGreeting: String = {         //[unowned self] in         return "Hello, \(self.name)!"         }()      init(name: String) {         print("person init")         self.name = name     }      deinit {         print("person deinit")     } } 

Used it like this

//... let person = Person(name: "name") print(person.personalizedGreeting) //.. 

And found that "person deinit" was logged.

So it seems there are no retain cycles. As per my knowledge when a block captures self and when this block is strongly retained by self, there is a retain cycle. This case seems similar to a retain cycle but actually it is not.

Answer 1

I tried this [...]

lazy var personalizedGreeting: String = { return self.name }() 

it seems there are no retain cycles

Correct.

The reason is that the immediately applied closure {}() is considered @noescape. It does not retain the captured self.

For reference: Joe Groff's tweet.