ios - Unwind segue (D->B) does not release C -

this swift 2.1 project ios 8.0+ target.

much user cybermew in this question, have set-up a->b->c->d. navigation controller , rest regular uiviewcontrollers. when unwinding d b, c not released. results in memory leak , other unintended side-effects.

as opposed question linked above, don't have nstimer know of might keep view in memory. causing happen?

code of c (trimmed):

import uikit import spritekit import avfoundation import avfoundation.avaudiosession  class gameviewcontroller: uiviewcontroller {  var scene: gamescene! var level: level!  @iboutlet weak var gameoverpanel: uiimageview! @iboutlet weak var heropicture: uiimageview! @iboutlet weak var villainpicture: uiimageview! @iboutlet weak var spellonebutton: uibutton! @iboutlet weak var doublelife: uiswitch!  let attacksound = skaction.playsoundfilenamed("attack.wav", waitforcompletion: false)  var tapgesturerecognizer: uitapgesturerecognizer!  var backgroundmusic: avaudioplayer = {      let sess = avaudiosession.sharedinstance()     if sess.otheraudioplaying {         _ = try? sess.setcategory(avaudiosessioncategoryambient, withoptions: [])         _ = try? sess.setactive(true, withoptions: [])     }      let url = nsbundle.mainbundle().urlforresource("backgroundmusic", withextension: "mp3")     let player = try? avaudioplayer(contentsofurl: url!)     player!.numberofloops = -1      return player! }()  override func prefersstatusbarhidden() -> bool {     return true }  override func shouldautorotate() -> bool {     return true }  override func supportedinterfaceorientations() -> uiinterfaceorientationmask {     return uiinterfaceorientationmask.allbutupsidedown }  override func viewdidload() {     super.viewdidload()      let skview = view as! skview     skview.multipletouchenabled = false      scene = gamescene(size: skview.bounds.size)     scene.scalemode = .aspectfill      level = level(filename: "level_0")     scene.level = level     scene.addtiles()     scene.swipehandler = handleswipe      skview.presentscene(scene)     backgroundmusic.play()     begingame() } } 

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moved here chat:

swipehandler declared as:

var swipehandler: ((swap) -> ())? 

and swap is:

struct swap: customstringconvertible, hashable {       // blabla } 

and once filled swap if calls on gameviewcontroller:

func handleswipe(swap: swap) {       view.userinteractionenabled = false       if level.ispossibleswap(swap) {          level.performswap(swap)          scene.animateswap(swap, completion: handlematches)      } else {          scene.animateinvalidswap(swap) {          self.view.userinteractionenabled = true      }  }  

you have reference loop causing viewcontroller not deallocated. recommend turning swipehandler weak delegate pointer , can call handleswipe though pointer. way, gamescene not retain strong pointers gameviewcontroller allow freed when unwind segue performed.

protocol swipehandler: class {     func handleswipe(swap: swap) }  class gameviewcontroller: uiviewcontroller, swipehandler {      var level = level()     var scene: gamescene!      override func viewdidload() {         super.viewdidload()          scene = gamescene()         scene.swipehandler = self     }      func handleswipe(swap: swap) {         // ...         } }  class gamescene {     weak var swipehandler: swipehandler?      // function demonstrate call handleswipe     func useswipehandler() {         let swap = swap()         swipehandler?.handleswipe(swap)     } }