Swift 解析：无法从帖子中检测喜欢的Id以启用喜欢的图像

//上面的部分用于显示like count，它可以工作。

        var showTopicLikeNumber = PFUser.query()
        showTopicLikeNumber.whereKey("liked", equalTo: topic.objectId)

        showTopicLikeNumber.findObjectsInBackgroundWithBlock({
        (objects:[AnyObject]!,error:NSError!)->Void in

        if (error == nil){
            let liked:NSArray = objects as NSArray
            cell.upvoteButton.setTitle("\(liked.count)", forState: UIControlState.Normal)
        }

      func topicTableViewCellDidTouchUpvote(cell: TopicTableViewCell, sender: AnyObject) {
      if PFUser.currentUser() != nil{

      let senderButton:UIButton = sender as UIButton
      var topicLiked:PFObject =      
      timelineTopicData.objectAtIndex(senderButton.tag) as PFObject

      println(topicLiked.objectId)

      PFUser.currentUser().addUniqueObject(topicLiked.objectId, forKey: "liked")
      PFUser.currentUser().save()

      senderButton.setImage(UIImage(named:"icon-upvote-active"), forState: UIControlState.Normal)
    }

    else{
        performSegueWithIdentifier("loginTopicSegue", sender: self)
    }
    }

//以上部分是针对tableviewcell中upvote按钮单元格的我的iAction的委托方法。

        var showTopicLikeNumber = PFUser.query()
        showTopicLikeNumber.whereKey("liked", equalTo: topic.objectId)

        showTopicLikeNumber.findObjectsInBackgroundWithBlock({
        (objects:[AnyObject]!,error:NSError!)->Void in

        if (error == nil){
            let liked:NSArray = objects as NSArray
            cell.upvoteButton.setTitle("\(liked.count)", forState: UIControlState.Normal)
        }

      func topicTableViewCellDidTouchUpvote(cell: TopicTableViewCell, sender: AnyObject) {
      if PFUser.currentUser() != nil{

      let senderButton:UIButton = sender as UIButton
      var topicLiked:PFObject =      
      timelineTopicData.objectAtIndex(senderButton.tag) as PFObject

      println(topicLiked.objectId)

      PFUser.currentUser().addUniqueObject(topicLiked.objectId, forKey: "liked")
      PFUser.currentUser().save()

      senderButton.setImage(UIImage(named:"icon-upvote-active"), forState: UIControlState.Normal)
    }

    else{
        performSegueWithIdentifier("loginTopicSegue", sender: self)
    }
    }

---

当用户已经喜欢一篇文章时，我想显示一个活动的喜欢的图像，尽管它能够显示，因为我在iAction中按upvote按钮时启用了喜欢的图像。但不幸的是，在重新登录系统后，它并没有在帖子上显示人们喜欢的主动向上投票的图像。

我想你只是需要一点概念火花。你可以试试这样的。对不起，我还不知道斯威夫特，但希望你能转换我的Obj-C来解决你的问题

       var showTopicUpvoteEnable = PFQuery(className: "Topics")
       showTopicUpvoteEnable.whereKey("objectId", equalTo:PFUser.currentUser().valueForKey("liked"))

       showTopicUpvoteEnable.findObjectsInBackgroundWithBlock({
       (objects:[AnyObject]!,error:NSError!)->Void in
       if error == nil{
      cell.upvoteButton.setImage(UIImage(named:"icon-upvote-active"), forState: UIControlState.Normal)}   
      else{
      cell.upvoteButton.setImage(UIImage(named: "icon-upvote"), forState: UIControlState.Normal)}
                })

并将下面的代码放入您的表格视图单元格中，以获得rowatinexpath

- (void)didTapStarButtonAction:(UIButton *)button{

    ...     

    // check if current user already liked the post
    if (![[object objectForKey:@"whoLiked"]containsObject:[PFUser currentUser].objectId]) {

        //add the object ID for the cell we are liking to the array of liked items in the user class in parse
        [[PFUser currentUser] addUniqueObject:object.objectId forKey:@"liked"];
        [[PFUser currentUser] saveInBackground];

        //add the user ID to the post that the user liked
        [object addUniqueObject:[PFUser currentUser].objectId forKey:@"whoLiked"];
        [object saveInBackground];

    } else {

        //remove the object ID for the cell we are liking to the array of liked items in the user class in parse
        [[PFUser currentUser] removeObject:object.objectId forKey:@"liked"];
        [[PFUser currentUser] saveInBackground];

        //remove the user ID to the post that the user liked
        [object removeObject:[PFUser currentUser].objectId forKey:@"whoLiked"];
        [object saveInBackground];

    }

    [self.tableView reloadData];
}

---

在Swift中执行类似操作的类似方式：

//star
UIButton *starButton = (UIButton*) [cell.contentView viewWithTag:kPAWCellStarButtonTag];

if ([[object objectForKey:@"whoLiked"]containsObject:[PFUser currentUser].objectId]) {
    [starButton setImage:[UIImage imageNamed:@"pressedStar.png"] forState:UIControlStateNormal];
} else {
    [starButton setImage:[UIImage imageNamed:@"unpressedStar.png"] forState:UIControlStateNormal];
}