ios - Parse.com - 就像我的应用程序中的系统

Question

我的喜欢的系统似乎有点慢。我将粘贴下面的代码，但我想先解释一下代码。当用户按下“likeButton”来喜欢内容时，它首先检查用户是否已经喜欢该内容。如果用户喜欢它，它就会喜欢该内容，如果用户不喜欢该内容，它就会喜欢它。

@IBAction func likeButtonAction(sender: AnyObject) {

        let buttonPosition = sender.convertPoint(CGPointZero, toView: self.collectionView)
        let indexPath = self.collectionView.indexPathForItemAtPoint(buttonPosition)

        let post = self.arrayOfDetails[indexPath!.item]

        let cell = collectionView.cellForItemAtIndexPath(indexPath!) as! CollectionViewCell

        cell.likeButton.enabled = false

        let query = PFObject(withoutDataWithClassName: "userUploads", objectId: self.arrayOfDetails[indexPath!.row].objID)
        if (post.likedBy.containsObject((PFUser.currentUser()?.username)!)) {
            query.removeObject((PFUser.currentUser()?.username)!, forKey: "likedBy")
            print("STEP 1: Current user removed from likedBy column")

            //Save
            query.saveInBackgroundWithBlock {
                (success: Bool, error: NSError?) -> Void in
                if (success) {
                    // The object has been incremented
                    print("STEP 2: Successfully saved")
                    post.likedBy
                    cell.likeButton.setBackgroundImage(self.Like, forState: .Normal)
                    self.queryCurrentUploads()

                } else {
                    // There was a problem, check error.description
                    //println(error!.description)
                }
            }
        }
        else{
            query.addObject((PFUser.currentUser()?.username)!, forKey: "likedBy")
            print("STEP 1: Current user added to likedBy column")

            // Save
            query.saveInBackgroundWithBlock {
                (success: Bool, error: NSError?) -> Void in
                if (success) {
                    // The object has been incremented
                    print("STEP 2: Successfully saved")
                    cell.likeButton.setBackgroundImage(self.LikeDone, forState: .Normal)
                    self.queryCurrentUploads()

                } else {
                    // There was a problem, check error.description
                    //println(error!.description)
                }
            }
        }
    }

我可以做些什么来简化代码，因为这段代码需要 1-2 秒才能完成，当我查看 Instagram 时，它会在 1 秒内点赞/不点赞。

Answer 1

让我们看看，一旦执行检查，您就会更新您的类似图像。
那绝对没问题。但如果您在更新对象之前实际保留代码，速度会更快。
例如，

if (post.likedBy.containsObject((PFUser.currentUser()?.username)!)) {
            query.removeObject((PFUser.currentUser()?.username)!, forKey: "likedBy")
            print("STEP 1: Current user removed from likedBy column")

            //Save
            query.saveInBackgroundWithBlock {
                (success: Bool, error: NSError?) -> Void in
                if (success) {
                    // The object has been incremented
                    print("STEP 2: Successfully saved")
                    post.likedBy
                    cell.likeButton.setBackgroundImage(self.Like, forState: .Normal)
                    self.queryCurrentUploads()

                } else {
                    // There was a problem, check error.description
                    //println(error!.description)
                }
            }
        }

不要在保存对象后更改点赞状态，而是在检查对象是否被点赞后立即更改。

所以可以是这样的，

 if (post.likedBy.containsObject((PFUser.currentUser()?.username)!)) {
        cell.likeButton.setBackgroundImage(self.Like, forState: .Normal)
        query.removeObject((PFUser.currentUser()?.username)!, forKey: "likedBy")
        print("STEP 1: Current user removed from likedBy column")
                query.saveInBackgroundWithBlock {
                    (success: Bool, error: NSError?) -> Void in
                    if (success) {
                        // The object has been incremented
                        print("STEP 2: Successfully saved")
                        post.likedBy

                        self.queryCurrentUploads()

                    } else {
                        // There was a problem, check error.description
                        //println(error!.description)
                    }
                }
            }

为什么这么慢？
问题是您的控件打开一个新线程，在其中执行所有保存和更新任务。一旦完成，您的“赞”按钮的图像将被更新。

其次，
当使用单元格加载表格 View 或 View 时，只需检查该帖子是否已被喜欢，因此这会减少一点时间(可以忽略不计，但当您拥有庞大的数据集时很有用)。

希望这有帮助。

----编辑----

@IBAction func likeButtonAction(sender: AnyObject) {

    let buttonPosition = sender.convertPoint(CGPointZero, toView: self.collectionView)
    let indexPath = self.collectionView.indexPathForItemAtPoint(buttonPosition)

    let post = self.arrayOfDetails[indexPath!.item]

    let cell = collectionView.cellForItemAtIndexPath(indexPath!) as! CollectionViewCell

    cell.likeButton.enabled = false

    let query = PFObject(withoutDataWithClassName: "userUploads", objectId: self.arrayOfDetails[indexPath!.row].objID)
    if (post.likedBy.containsObject((PFUser.currentUser()?.username)!)) {
        cell.likeButton.setBackgroundImage(self.Like, forState: .Normal)
        query.removeObject((PFUser.currentUser()?.username)!, forKey: "likedBy")
        print("STEP 1: Current user removed from likedBy column")

        //Save
        query.saveInBackgroundWithBlock {
            (success: Bool, error: NSError?) -> Void in
            if (success) {
                // The object has been incremented
                cell.likeButton.enabled = true;
                print("STEP 2: Successfully saved")
                self.queryCurrentUploads()

            } else {
                // There was a problem, check error.description
                //println(error!.description)
            }
        }
    }
    else{
        cell.likeButton.setBackgroundImage(self.LikeDone, forState: .Normal)
        query.addObject((PFUser.currentUser()?.username)!, forKey: "likedBy")
        print("STEP 1: Current user added to likedBy column")

        // Save
        query.saveInBackgroundWithBlock {
            (success: Bool, error: NSError?) -> Void in
            if (success) {
                // The object has been incremented
                print("STEP 2: Successfully saved")
                cell.likeButton.enabled = true;
                self.queryCurrentUploads()

            } else {
                // There was a problem, check error.description
                //println(error!.description)
            }
        }
    }
}

我没有做太多事情，只是在 savInBackground 函数之前移动了一些行。其次，一旦您的查询完成，我就启用了该按钮。那是在保存功能中。
这将很有帮助，因为一旦通过类似或删除类似更新了解析表，该按钮将默认启用。

干杯!