加载较早，滚动流畅

Question

I am working on chat application. In my app load earlier message feature implemented which is not smooth and accurate like whatsapp .

I am using UITableview for chat listing and fetching more data using

func scrollViewDidScroll(_ scrollView: UIScrollView) {

    if scrollView.contentOffset.y >= 0 &&  scrollView.contentOffset.y <= 50{
        print(" scrollViewDidScroll Load Earlier start- \(Utils.stringFromNSDate(Date(), inMillisec: true, useUTC: true)!)")
         if !self.messageFetcher.isHideLoadMoreDisplay{
            if self.messageFetcher.arrayOfallChatMessagesData.count > 0 && !isCheckLoading{
                self.isCheckLoading = true
                let message = self.messageFetcher.arrayOfallChatMessagesData[0]
                self.messageIdForMessageDisplay =  (message.chatMessageId )
                self.loadMoreDataLoad(threadId: self.messageFetcher.chatThreadId, isloadFromServer: false)
            }
        }
         print(" scrollViewDidScroll Load Earlier end- \(Utils.stringFromNSDate(Date(), inMillisec: true, useUTC: true)!)")
    }
}

So, Which is better way to achieve load earlier with smoothness same as like whatspp Application.

Answer 1

You should always load your data in CellForWowatIndexpath method, and also use pagination and load more data when that last cell is displayed. You can call load more method on cellWillDisplay method. And last but not least if you are loading images use SDWebimage to load the image so that the scrolling becomes smooth

 func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

   // load dats here



    return cell
}

Reload the data when last cell is visible

 func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
    let lastItem = self.YourArray.count - 1

        if indexPath.row == lastItem
        {
            //call load more data method
        }

    else{
        return
    }
}