pavbaranov  filed a deletion request for apper :
It seems, that this application is abandoned even by upstream. We haven't got packagekit-qt4 (one of its dependency) even in AUR. So there is impossible to build it.
 https://aur.archlinux.org/account/pavbaranov/  https://aur.archlinux.org/pkgbase/apper/
Request #9654 has been accepted by Muflone .