Parse: Cannot detect liked Id from a post to enable a Liked image

Question

        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)
        }

// The above part is for displaying like count, and it works.

      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)
    }
    }

// The above part is for delegate method of my IBAction of upvote button cell from tableviewcell.

       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)}
                })

I want to show an active liked image when a user already liked a post, though it is able to show since I enable a liked image in IBAction when press the upvote button. But unluckily, it does not display the active upvote image on the post that one liked after one re-login into the system.

Answer 1

I think you just need a spark of concept around this. You may try something like this. Sorry I don't know Swift yet but hopefully you can convert my Obj-C to solve your problem.

- (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];
}

And put the below code in your tableView cellForRowAtIndexPath

//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];
}