ios - How do i display UIAlertController from any NSObject subclass? -

i have legacy codebase managing, needs display alert messages on place. terrible practice , in need of refactor, isn't going happen time soon. ios 9 need ability fire & forget alert view, , have view display , queuing managed me.

to show, uialertcontroller, need object of uiviewcontroller can use below way that.

 uiwindow *keywindow = [[uiapplication sharedapplication]keywindow];  uiviewcontroller *maincontroller = [keywindow rootviewcontroller];  [maincontroller presentviewcontroller:alert animated:yes completion:nil]; 

thanks