ios - UIPageViewController second and third page flickers to white -

i have pageviewcontroller, when swipe second page, shows right controller split second , screen goes white, if swipe again show should be. has 4 pages instead of intended 3 pages.

here video demonstrate problem: https://streamable.com/i1inq

the indexing following:

 profilecontroller.index = 0  discovercontroller.index = 1  matchcontroller.index = 2  func pageviewcontroller(_ pageviewcontroller: uipageviewcontroller, viewcontrollerafter viewcontroller: uiviewcontroller) -> uiviewcontroller? {     if index == 0     {         index = discovercontroller.index         return discovercontroller     }     else if index == 1     {         index = matchcontroller.index         return matchcontroller     }      return nil } 

edit: should mention initial controller profilecontroller, , index starts @ 0 when app run.

updated

you can modify code customized viewcontroller index property:

func pageviewcontroller(_ pageviewcontroller: uipageviewcontroller, viewcontrollerafter viewcontroller: uiviewcontroller) -> uiviewcontroller? {     let index = (viewcontroller as? mycustomvcwithindexforpageviewcontroller).index     if index == 0     {         index = discovercontroller.index         return discovercontroller     }     else if index == 1     {         index = matchcontroller.index         return matchcontroller     }      return nil } 

original

you should not cache parameter related pageviewcontroller. uipageviewcontroller preload page have better performance.

ex:

you have 3 pages display.

you displaying first page initial.

then scroll second view. viewcontrollerafter called viewcontroller of first viewcontroller requesting second viewcontroller.

and viewcontrollerafter called again viewcontroller of second viewcontrollerfor requesting third viewcontroller (preload).

in case if cache index, lead unpredictable results.