ios - 点赞按钮并非每次都有效

我正在尝试制作一个社交媒体应用程序，功能之一是点赞按钮，不幸的是，当您单击所有功能时，一切正常，但始终无法正确更新点赞和点赞按钮的次数。我认为这与刷新有关，但是我需要刷新它才能更新喜欢的数量。有人知道发生了什么吗...

func like(sender: AnyObject) {

    var buttonPosition: CGPoint = sender.convertPoint(CGPointZero, toView: self.table)

    var indexPath: NSIndexPath = self.table.indexPathForRowAtPoint(buttonPosition)!

    if sender.currentTitle == "Like" {
        sender.setTitle("Unlike", forState: .Normal)
        var addLikeQuery = PFQuery(className: "Post")

        addLikeQuery.whereKey("message", equalTo: self.messages[indexPath.row])

        addLikeQuery.findObjectsInBackgroundWithBlock { (aPosts, error) -> Void in
            if let aPosts = aPosts {
                for aPost in aPosts {
                    aPost.addUniqueObject(PFUser.currentUser()!.objectId!, forKey: "likers")
                    self.likeDisplayText = ((aPost["likers"] as! [String]).count - 1).description + " Like"
                    self.table.reloadRowsAtIndexPaths([indexPath], withRowAnimation: .None)
                    aPost.saveInBackgroundWithBlock({ (success, error) -> Void in
                        if error != nil {
                            self.likeDisplayText = "Couldn't Like Picture!"
                        }
                    })
                }
            }
        }

    } else {
        sender.setTitle("Like", forState: .Normal)
        var removeLikeQuery = PFQuery(className: "Post")

        removeLikeQuery.whereKey("message", equalTo: self.messages[indexPath.row])

        removeLikeQuery.findObjectsInBackgroundWithBlock { (rPosts, error) -> Void in
            if let rPosts = rPosts {
                for rPost in rPosts {
                    rPost.removeObject(PFUser.currentUser()!.objectId!, forKey: "likers")
                    self.likeDisplayText = ((rPost["likers"] as! [String]).count - 1).description + " Like"
                    self.table.reloadRowsAtIndexPaths([indexPath], withRowAnimation: .None)
                    rPost.saveInBackgroundWithBlock({ (success, error) -> Void in
                        if error != nil {
                            self.likeDisplayText = "Couldn't Like Picture!"

                        }
                    })

                }
            }
        }
    }
}

最佳答案

我不确定您的问题是什么，但我可能有一些见识。如果您试图通过执行大量处理或在另一个线程中的函数来编辑UI中的某些元素，建议将其设置为Asynchronus，并在要编辑UI的该函数中的任何位置使该代码在主线程上运行。这就是我的意思。

func like(sender: AnyObject) {
  dispatch_async(dispatch_get_global_queue(Int(QOS_CLASS_USER_INITIATED.value), 0)) {
    // do background stuff

    dispatch_async(dispatch_get_main_queue()) {
      // when you want to edit the text of the button
      // or change something in your UI
      // do it in here
      self.likeDisplayText = "Couldn't Like Picture!"
    }
  }
}