在解析中使用用户的朋友列表更新Tableview

Question

I'm using Parse to add friend's username to current user object with PFRelation and I want to retrieve it to appear at friend list view controller. This is my code for retrieving current user friend list's object and updating tableview to show current user's latest friend list. My class in Parse that save all my app's registered user is "User".
Here's my code in swift

var userArray: [String] = []
var usernames:[String] = [""]
var userids :[String] = [""]

override func viewDidLoad() {
    super.viewDidLoad()
    var query = PFUser.query()
    var currentUser = PFQuery(className:"User")
    currentUser.whereKey("currentUser", equalTo: PFUser.currentUser())

    currentUser.findObjectsInBackgroundWithBlock({ (objects:PFObject, error:NSError) -> Void in  // <- error here says that Expression resolves to an unused function
        if objects != nil { // <- error here says that cannot invoke != with an argument list of type(PFObject,NilLiteralConvertible)
            let users = objects
            self.users.removeAll(keepCapacity: true)
            self.usernames.removeAll(keepCapacity: true)

            for object in users {
                if let user = object as? PFUser {
                    userArray.append(user.username)
                }
            }
            else {  // <- error here says that Expected expression
                println("Error")
            }
        }
    }
}

The problem is that my tableview shows nothing, it's just an empty tableview but when I check at parse.com, the current user's relation exists and all the user's that I've add exist in that relation so the problem is to retrieve current user's object and update the tableview.
Any help is appreciated and let me know if you need any additional information.

Thank you!

Answer 1

Since you're getting data asynchronously the UI does not know when to update. You need to update the UI once you have all of your data.

Try putting self.tableView.reloadData() after the for loop in your findObjectsInBackgroundWithBlock block