Scroll to specific Message Item

[seidju]

Hi @AntonPalich , I want to implement Reply functionality, so user, after he taps on "replied" message scrolls to original message.
The main problem is, that sliding data source doesn't give me all items at once, so before scrolling, I need to add messages to dataSource, something like this:

func loadPrevious(completion: (() -> ())?) {
    slidingWindow.loadPrevious()
    slidingWindow.adjustWindow(focusPosition: 0, maxWindowSize: preferredMaxWindowSize)
    delegate?.chatDataSourceDidUpdate(self, completion: completion) //add completion block for dataSource update
  }

Now, I call something like recursively append images to SlidingDataSource, until desired messageId would contains in chatItems :

fileprivate func scrollToItem(index: Int, messageId: String) {
    if dataSource.chatItems.contains(where: { $0.uid == messageId }) {
      let ip = IndexPath(item: index, section: 0)
      //scroll ???
    } else {
      dataSource.loadPrevious { [weak self] in
        self?.scrollToItem(index: index, messageId: messageId)
      }
    }
  }

My question - how to scroll to this message, even if it's already in chatItems. I tried to just use

      collectionView.scrollToItem(at: ip, at: .centeredVertically, animated: true)

but I got an error ,that cell at ip is doesn't exist.
Thanks for any help or advice!

[Xopoko]

Same question. Has anyone already been able to fix it? The issue has been open since February 6.

[spacedema]

Have the same issue. Any workaround?

[Daxito]

+1

[seidju]

Hi everyone!
Any updates on this issue?
I tried on latest release, using scrollToItem(withId: uid), but still no effect. In this function - property
let isScrollingUp = rect.minY < collectionView.contentOffset.y always return false
Here's code snippet:

 if let index = self?.chatItemCompanionCollection.indexOf(messageModel.uid),
        let uid = self?.chatItemCompanionCollection[index].uid {
        self?.scrollToItem(withId: uid, position: .centeredVertically, animated: true)
      }

[AntonPalich]

@seidju I just checked the demo app. I modified handleTapOnScrollToBottomButton function to scroll to the first item when you tap "Scroll to bottom" button on "Scroll To Bottom Button Example" screen. It worked for me.

    @objc
    private func handleTapOnScrollToBottomButton() {
        guard self.chatItemCompanionCollection.count > 0 else { return }

        let startIndex = self.chatItemCompanionCollection.startIndex
        self.scrollToItem(withId: self.chatItemCompanionCollection[startIndex].uid, position: .top, animated: true)
    }

Having isScrollingUp == false doesn't mean that it doesn't work. Your item can be visible on a screen, or you have not enough items to make a scroll action. Could you provide a list of items when you try to scroll, a screen from your app and id of a messageModel.uid?

[seidju]

@AntonPalich Yep, I just checked it again and it was my stupid mistake (used wrong uid). Everything works great, as expected. Sorry for that )
Closing this issue!