ios - 多个查询返回错误结果

Question

我正在使用 parse 来尝试创建一个 Instagram 风格的应用程序，用户可以在其中关注其他用户。下面的代码尝试查询我的解析数据库并检查登录的用户是否“关注”另一个用户。它当前进入您可以看到“ENTERS HERE BUT DOES NOT APPEND”的位置。两个问题:1. 为所有用户输入此位置，而不仅仅是当前登录用户关注的用户2.append.isfollowing 不起作用。最初，isfollowing.count是0，当我再次在末尾打印它时，它仍然是0。即使它进入了它包含的if语句，追加也不起作用下面的代码 - 谢谢!

var usernames = [""]
var userids = [""]
var isFollowing = [Bool]()

override func viewDidLoad() {
    super.viewDidLoad()


    var query = PFUser.query()
    query?.findObjectsInBackgroundWithBlock({ (objects, error) -> Void in

        //check if we have any objects
        if let users = objects {

            //for each element in the users array
            for object in users {

                //convert to PFuser
                if let user = object as? PFUser {

                        //check if the current user is following each user. if so update isfollowing array
                        var query = PFQuery(className: "followers")

                        query.whereKey("follower", equalTo: PFUser.currentUser()!.objectId!)
                        query.whereKey("following", equalTo: user.objectId!)


                        query.findObjectsInBackgroundWithBlock({ (objects, error) -> Void in
                            //if objects returns something
                            if let objects = objects {

                                //if we enter here we know that the logged in user is following the curr user. Update the isfollowing array
                                //ENTERS HERE BUT DOES NOT APPEND
                                self.isFollowing.append(true)

                            } else {
                                self.isFollowing.append(false)
                            }
                        })   
                }
            }
        }
        //reload the table data
        self.tableView.reloadData()
    })

        print(self.isFollowing.count)

Answer 1

1. It is entering this location for all users, not just the ones that the currently logged in

由内部查询测试的条件，if letobjects=objects 测试数组是否已定义(非零)。您想要的是测试数组是否非零且非空，例如:

if objects?.count > 0 {  // we found at least one

2. the append.isfollowing is not working

附加到 isFollowing 的代码异步运行。 viewDidLoad 末尾的打印语句在查询完成之前立即运行。这就是为什么它看起来不起作用(它只是还没有起作用)。