ios - Unbalanced calls to begin/end appearance transitions with custom segue -

in implementing following cross-dissolve custom segue on button press (learned @ https://www.youtube.com/watch?v=xq9zvslncww):

override func perform() {      var src:uiviewcontroller = self.sourceviewcontroller as! uiviewcontroller     var dstn:uiviewcontroller = self.destinationviewcontroller as! uiviewcontroller      src.view.addsubview(dstn.view)     dstn.view.alpha = 0      uiview.animatewithduration(0.75 , delay: 0.1, options: uiviewanimationoptions.transitioncrossdissolve, animations: { () -> void in           dstn.view.alpha = 1       }) { (finished) -> void in          dstn.view.removefromsuperview()         src.presentviewcontroller(dstn, animated: false, completion: nil)      }  } 

i getting "unbalanced calls begin/end appearance transitions" warning/error.

i have thoroughly searched many stackoverflow questions:

unbalanced calls begin/end appearance transitions <uitabbarcontroller: 0x197870>

• my response: using segue button press not within tabbar controller answer not apply

keep getting "unbalanced calls begin/end appearance transitions <viewcontroller>" error

• my response: tried 2 methods: 1) segues done programatically self.performseguewithidentifier 2) segues done via interface builder, click dragging buttons , selecting custom transition attributes pane of selected segue. both still yielded aforementioned error.

"unbalanced calls begin/end appearance transitions" warning when push view in modal way in xcode 4 storyboard

• my response: same above, double checked segues performed once, either programmatically or via interface builder, not both.

"unbalanced calls begin/end appearance transitions detailviewcontroller" when pushing more 1 detail view controller

• my response: not using table view controller nor navigation controller in segues, answer not apply.

unbalanced calls begin/end appearance transitions uitabbarcontroller

• my response: tried making segues perform within dispatch shown below

  let delay = 0.01 * double(nsec_per_sec) let time = dispatch_time(dispatch_time_now, int64(delay)) dispatch_after(time, dispatch_get_main_queue()) {     self.performseguewithidentifier("tononfblogin", sender: nil)   } 

however still no avail, warning/error still pops up.

i'm aware error means, it's attempting present new viewcontroller before previous 1 loads, not sure how tackle it.

the lead have previous (source) viewcontroller pops real before final viewcontroller loads, seen @ 0:04 @

https://youtu.be/i1d5fbcjnjy

the glitch appears guess around 5% of time, however.

any ideas?

looks behaviour result of - of yet - undocumented change in recent ios releases. getting frustrated exact issue , lack of satisfying answers i've come this:

// create uiimageview containing uiimage of `view`'s contents func createmockview(view: uiview) -> uiimageview {     uigraphicsbeginimagecontextwithoptions(view.frame.size, true, uiscreen.mainscreen().scale)      view.drawviewhierarchyinrect(view.bounds, afterscreenupdates: true)     let image = uigraphicsgetimagefromcurrentimagecontext()      uigraphicsendimagecontext()     return uiimageview(image: image) }  override func perform() {     let src:uiviewcontroller = self.sourceviewcontroller as! uiviewcontroller    let dstn:uiviewcontroller = self.destinationviewcontroller as! uiviewcontroller    let mock = createmockview(dstn.view)     src.view.addsubview(mock)    mock.alpha = 0     uiview.animatewithduration(0.75, delay: 0.1, options: uiviewanimationoptions.transitioncrossdissolve,       animations: { () -> void in         mock.alpha = 1      },      completion: { (finished) -> void in         src.presentviewcontroller(dstn, animated: false, completion: { mock.removefromsuperview()})    }) } 

createmockview() create uiimageview containing snapshot of destination vcs contents , use transition animation. once transition finished real destination vc presented without animation causing seamless transition between both. once presentation done mock view removed.