Can't add self as subview

[imnotok]

'DAKeyboardControl.m' line 553, column 1 with start address 0x0000000100215854

Sometimes it will crash here

[CavalcanteLeo]

im getting the same crash

[michaelMaoMao]

Maybe it`s pushing 2 VC at same time, which cause the pushing animation problem, refer to
https://stackoverflow.com/questions/19560198/ios-app-error-cant-add-self-as-subview
and you may find solution on this :
http://lengmolehongyan.github.io/blog/2015/10/30/cant-add-self-as-subview-beng-kui-jie-jue-ban-fa/

just make sure the there is one VC on transition progress at same time,.