如何在查询后运行pageViewController实例化？

Question

我正在尝试将导入的解析信息添加到pageviewcontroller，但它会一直崩溃，因为所有数组都是nil，而第二个函数是在早期调用的。我该如何解决这个问题？

override func viewDidLoad() {
    super.viewDidLoad()

    self.retrieveInfo() { () -> () in
        self.testRetrieveInfo()
    }

}


func retrieveinfos(handleComplete:(()->())){

 let query = PFQuery(className: "Animals")
    query.findObjectsInBackgroundWithBlock { (objects:[PFObject]?, error: NSError?) in
            if(error == nil){
                for object in objects!{     
                    if let importname = object["Name"] as? String{
                        self.name.append(importname)
                        print(self.name)
                    }
                }

            }else{
                    print(error)
            }
        }
      handleComplete()
   }
}


func testRetrieveInfo(){

        //Setup here the PageViewController
        self.pageViewController.storyboard?.instantiateViewControllerWithIdentifier("PageVC") as? UIPageViewController //Crashes here, with fatal error fatal error: unexpectedly found nil while unwrapping an Optional value, I checked the logs and all the arrays are empty
        self.pageViewController.dataSource = self
        var startVC = self.viewControllerAtIndex(0) as? Animal
        var viewControllers = NSArray(object: startVC!)
        self.pageViewController.setViewControllers(viewControllers as? [UIViewController], direction: .Forward , animated: true, completion: nil)
        self.pageViewController.view.frame = CGRectMake(0, 30, self.view.frame.width, self.view.frame.height)
        self.addChildViewController(self.pageViewController)
        self.view.addSubview(self.pageViewController.view)
        self.pageViewController.didMoveToParentViewController(self)
        print("called")

}