How to sort Object Array from a PFQuery?

Question

Hi I have a PFQuery where I am retrieving map images and I need to sort them so that i can retrieve the correct image in my code. This is currently my code:

func retrieveImages() {
        self.imageArray = [UIImage]()
        var query = PFQuery(className:"Maps")
        query.orderByDescending("createdAt")
        query.findObjectsInBackgroundWithBlock {
            (objects: [AnyObject]?, error: NSError?) -> Void in
            if error == nil {
                if let objects = objects as? [PFObject] {
                    for object in objects {
                        self.objectNames.append(object["Name"]!)
                        let userImageFile = object["imageFile"] as! PFFile
                        userImageFile.getDataInBackgroundWithBlock {
                            (imageData: NSData?, error: NSError?) -> Void in
                            if error == nil {
                                if imageData != nil {
                                    let imageData = imageData
                                    var image = UIImage(data:imageData!)
                                    if image != nil {
                                        self.imageArray.append(image!)
                                    }
                                }
                            }
                        }
                    }
                }
            }
        }
    }

I tried to sort the query by using the orderByDescending function but when i run the code only the names of the objects are sorted and the images themselves are not. There also seems to be no pattern in how the images are sorted because each time I run this code the order of the images are different. Any advice or insight would be appreciated.