completion at presentViewController ; what is

The completion block is used for doing any tasks
after presenting the view controller

reference

thanks for your knowledge sharing

<a href="http://stackoverflow.com/questions/13025026/what-should-go-into-completion-in-presentviewcontroller">what should go into completion in presentViewController?</a>stackoverflow.com

<a href="https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIViewController_Class/#//apple_ref/occ/instm/UIViewController/presentViewController:animated:completion:">UIViewController Class Reference</a>developer.apple.com