Test if closures alone create reference cycles

ClosuresReferenceCycle.playground

import Foundation

class Alf {
    static var numberOfInstances = 0
    init() {
        Alf.numberOfInstances += 1
        print("Alf instances: \(Alf.numberOfInstances)")
    }
    deinit {
        Alf.numberOfInstances -= 1
        print("Alf instance: \(Alf.numberOfInstances)")
    }
}

class Bernd {
    static var numberOfInstances = 0
    let grillen:String
    init(grillen:String = "gepflegt") {
        self.grillen = grillen
        Bernd.numberOfInstances += 1
        print("Bernd instances: \(Bernd.numberOfInstances)")
    }
    deinit {
        Bernd.numberOfInstances -= 1
        print("Bernd instance: \(Bernd.numberOfInstances)")
    }

}

var closure: (() -> (() -> ()))?

closure = {
    _ in
    var bernd = Bernd()
    var innerClosure : () -> () = {
        _ in
        print(bernd.grillen)
        var alf = Alf()
    }
    bernd = Bernd(grillen: "ungepflegt")
    return innerClosure
}

var secondClosure: (()->())? = closure!()
secondClosure!()
secondClosure!()

secondClosure = nil

prints:

Bernd instances: 1
Bernd instances: 2
Bernd instance: 1
ungepflegt
Alf instances: 1
Alf instance: 0
ungepflegt
Alf instances: 1
Alf instance: 0
Bernd instance: 0

So everything should get collected by GC deallocated, ARC seems not to be problematic in this case!