在Swift中访问外部变量

Question

I want to access "posts" outside this function so that I can call tableview.reloaddata() outside the function. The code under calls tableview.reloaddata() everytime a key has entered the qeoquery. I want to only reload it one time. But when I try in viewDidLoad, the "posts" array is empty. What to do?

Posts declared outside function:

var  posts = [Post]()

Function:

func fetchData(){


        geofireRef = Database.database().reference().child("LOCATION")
        geofire = GeoFire(firebaseRef: geofireRef)
        let geoQuery = geofire?.query(at: myLoc, withRadius: 5.0)

        geoQuery?.observe(.keyEntered, with: { (key: String!, location: CLLocation!) in
            print("KEYKEY: \(key)")
            let dbRef = Database.database().reference().child("posts")
            let query = dbRef.queryOrdered(byChild: "\(key)")
            query.observeSingleEvent(of: .value, with: { (snapshot) in
                if let snapshot = snapshot.children.allObjects as? [DataSnapshot]{
                    for snap in snapshot {
                        if let postDict = snap.value as? Dictionary<String, Any>{
                            let key = snap.key
                            let post = Post.init(postKey: key, postData: postDict)


                            self.posts.append(post)
                        }
                    }
                }
                //self.posts.reverse()
                //self.tableView.reloadData()
                //print("POSTS: \(self.posts)")
            })
        })
    }

Answer 1

You can either call tableView.reloadData() right after setting your posts variable (like you have commented out), or you can put a didSet observer on your posts variable and reload your tableView after it's set. If you go with that second option you'll want to restructure your parser to set the posts only once, rather than appending items one at a time. That would look something like this:

var posts = [Post]() {
    didSet {
        self.tableView.reloadData()
    }
}

geoQuery?.observe(.keyEntered, with: { (key: String!, location: CLLocation!) in
        print("KEYKEY: \(key)")
        let dbRef = Database.database().reference().child("posts")
        let query = dbRef.queryOrdered(byChild: "\(key)")
        query.observeSingleEvent(of: .value, with: { (snapshot) in
            if let snapshot = snapshot.children.allObjects as? [DataSnapshot]{
                //Create a variable to hold posts until you've parsed all of them
                var foundPosts = [Post]()
                for snap in snapshot {
                    if let postDict = snap.value as? Dictionary<String, Any>{
                        let key = snap.key
                        let post = Post.init(postKey: key, postData: postDict)
                        foundPosts.append(post)
                    }
                }
                //Set the posts to be all the found posts
                self.posts = foundPosts
            }
        })
    })