处于自身功能时无法推送视图控制器

Question

I made A UIViewController which has a Completion handler function on it because it has to load data from a database, the code for the segue there is :

func S0000 () {

    let V = self.storyboard!.instantiateViewControllerWithIdentifier("V0003") as! V0003

    V.Cv { (Con) -> Void in

        NSOperationQueue.mainQueue().addOperationWithBlock {
            self.showViewController(V, sender: self)
        }
    }
}

This throws the error :

fatal error: unexpectedly found nil while unwrapping an Optional value

How could I make it work and what am I doing wrong.

And just for information I found out that when I run it this way It works but ofcours is not finished loading when pushing to It becuase It pushes before the completion handler returns.

func S0000 () {

    let V = self.storyboard!.instantiateViewControllerWithIdentifier("V0003") as! V0003

self.showViewController(V, sender: self)

    V.Cv { (Con) -> Void in
        NSOperationQueue.mainQueue().addOperationWithBlock {    
        }   
    }   
}

Answer 1

Try this

V.Cv { (Con) -> Void in

NSOperationQueue.mainQueue().addOperationWithBlock {
    let V = self.storyboard!.instantiateViewControllerWithIdentifier("V0003") as! V0003
    self.showViewController(V, sender: self)
    }
}