popToViewController Executing First

When the post button is pressed, the function below executes. In the function, all the objects that are retrieved using the Parse backend are appended to the groupConversation array, which is a global array. However, when I reference the array in the UITableViewController that is popped to towards the end of the function and use println() to print the content of the array, the array is empty. However, when I use println() in the UIViewController that contains this function the array is shown to contain one object. In the console, the println() of the UITableViewController that is popped to once the button is pressed, is executed before the println() of the UIViewController that contains the function below. How can I make the functon below execute completely before popping to the UITableViewController.

@IBAction func postButtonPressed(sender: AnyObject) {
    //Adds Object To Key
    var name=PFObject(className:currentScreen)
    name["userPost"] = textView.text
    name.saveInBackgroundWithBlock {
        (success: Bool!, error: NSError!) -> Void in

        if success == true {

            self.textView.text=""


        } else {

            println("TypeMessageViewController Error")

        }


    }
    //Gets all objects of the key
    var messageDisplay = PFQuery(className:currentScreen)
    messageDisplay.selectKeys(["userPost"])
    messageDisplay.findObjectsInBackgroundWithBlock {
        (objects: [AnyObject]!, error: NSError!) -> Void in
        if error == nil{
            for object in objects {
                var textObject = object["userPost"] as String
                groupConversation.append(textObject)

                }
        } else {
            // Log details of the failure

        }
        println("Type message \(groupConversation)")
    }
    navigationController!.popToViewController(navigationController!.viewControllers[1] as UIViewController, animated: true)
}