function - Where exactly is this object being stored? (Swift) -

consider following code:

class foo {  }  func foo() -> (void -> foo) {     var foo = foo()     return { foo } }  var foogen = foo() 

now whenever call foogen, stored foo instance. foo being stored? inside stack? , if so, it's lifetime?

both classes , closures reference types.

var foo = foo() 

creates foo object on heap, , stores (strong) reference object in local stack variable foo.

return { foo } 

creates closure captures foo, closure holds (strong) reference object. on return function, local foo variable goes out of scope, 1 reference closure remains.

var foogen = foo() 

makes foogen reference returned closure (which in turn has reference foo object):

foogen -> closure -> foo object 

so foo object exists long foogen reference exists (assuming no additional strong references created).

demo:

class foo {     deinit {         println("deinit")     } }  func foo() -> (void -> foo) {     var foo = foo()     return { foo } }  if true {     var foogen = foo()     println("foo") }  println("done") 

output:

 foo deinit done 

the object destroyed when program control leaves scope of foogen.