UITableView Scrolls To Undesired Index or Position - ios

Question

Basically the task is to load new API response as the user scrolls to down in UITableView without stopping user interaction and maintaining the current position (live feeds like Facebook and Instagram).
What I want to do is that parsing and then viewing Rest API's response in UITableView with custom cells.
The issue is that when the user scrolls to bottom the API call is made and table view scrolls to some other position where the user is.
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return UITableViewAutomaticDimension
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return array.count;
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "xxxxx", for:indexPath) as! xxxxxxxx
return cell;
}
func scrollViewDidEndDragging(_ scrollView: UIScrollView, willDecelerate decelerate: Bool) {
if scrollView == tableView {
if ((scrollView.contentOffset.y + scrollView.frame.size.height) >= scrollView.contentSize.height) {
print("Scroll Ended")
fetchDataFromApi()
}
}
}
func fetchDataFromApi() {
let jsonUrlString = "xxxxxxx"
guard let url = URL(string: jsonUrlString) else {
return
}
print(url)
URLSession.shared.dataTask(with: url) {(data,response,err) in
guard let data = data else {
return
}
do {
let apiResponseData = try JSONDecoder().decode(ApiResponse.self, from: data)
if apiResponseData.httpStatusCode == HttpStatusCode.OK {
if let apiResponse = apiResponseData.data{
self.array.append(contentsOf: apiResponse)
}
DispatchQueue.main.async {
self.tableView.reloadData()
}
}
else {
print("API Response Error : \(apiResponseData.httpStatusCode) \(apiResponseData.errorMessage)")
}
}catch let jsonErr {
print("Serialization Error \(jsonErr)")
}
}.resume()
}}

Answer 1

Try with this
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "xxxxx", for:indexPath) as! xxxxxxxx
let lastRowIndex = tableView.numberOfRows(inSection: tableView.numberOfSections-1)
if (indexPath.row == lastRowIndex - 1) {
//print("last row selected")
fetchDataFromApi()
}
return cell;
}
If you are using this so no need to call this method
scrollViewDidEndDragging

Answer 2

try insertCellAtIndexPath replace for tableview.reloadData() in
if let apiResponse = apiResponseData.data{
self.array.append(contentsOf: apiResponse)
}
DispatchQueue.main.async {
self.tableView.reloadData()
}
......

Answer 3

There are several ways to implement this. The most favourable as far as I see it is to implement a paginated API and call the API once the UITableView's last item. You may use:
public func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
let botEdge = scrollView.contentOffset.y + scrollView.frame.size.height;
if (botEdge >= scrollView.contentSize.height)
{
// Call API and reload TableView on completion handler.
}
}
Call the tableView reload on the completion handler of the API method.
Or you can do it in a slightly more awkward way:
public var indexPathsForVisibleRows: [NSIndexPath]? { get }
Get the array of index paths of the currently visible cells and scroll to the index after you reload the UITableView using:
tableView.tableView.scrollToRowAtIndexPath(indexPath, atScrollPosition: UITableViewScrollPosition.None, animated: false)

Answer 4

It was because of dynamic cell sizes I was setting in table view