Updating Table Value when it is scrolled - ios

Question

I need to display data in a cell, when the table gets loaded and when it is scrolled. I get data into the table rows the very first time the app is run, but when I scroll the table, the table does not update all values. It shows only the last fetched value from the service.
My Service request format is :
http://vapp.sites.net/......userId=967730&rowsPerPage=10&nextCursorMark=1
Note - when i call service, the NextCursorMark is increased at response, which i m passing to next service call at scroll time.When nextCursorMark is nil i have to stop scrolling the table because there s no more new response data.
Response :
{
MESSAGE: "Success",
STATUS_CODE: 200,
REQUEST: [ ],
RESPONSE: {
OrderList: [..<items>..],
nextCursorMark: "2",
totalOrderCount: 45
}
}
when the table gets loaded for the first time nextCursorMark value is 1 and on each scroll the value will be increased based on totalOrderCount. How can I manage the table view datasource when it is scrolled and the service is called, on each scroll?
My code below:
1 - when loading the Table
#pragma mark - UITableViewDataSource Methods
- (NSInteger)numberOfSectionsInTableView:(UITableView *)theTableView
{
return self.arrOrderList.count;
}
- (NSInteger)tableView:(UITableView *)theTableView numberOfRowsInSection:(NSInteger)section
{
OrderList * objOrderList = (OrderList *)[self.arrOrderList objectAtIndex:section];
return objOrderList.orderDetailsList.count;
}
- (UITableViewCell *)tableView:(UITableView *)theTableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *cellIdentifier = #"OrderDetailsListCell";
OrderDetailsListCell * cell = (OrderDetailsListCell *)[theTableView dequeueReusableCellWithIdentifier:cellIdentifier];
if (cell == nil) {
cell = [[OrderDetailsListCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier];
}
[cell setSelectionStyle:UITableViewCellSelectionStyleNone];
OrderList * objOrderList = (OrderList *)[self.arrOrderList objectAtIndex:indexPath.section];
OrderDetailsList * objOrderDetailsList = (OrderDetailsList *)[objOrderList.orderDetailsList objectAtIndex:indexPath.row];
[cell loadDataWithOrderDetailList:objOrderDetailsList];
return cell;
}
- (void) ServiceCallForOrderHistoryWithCurrentPageMark:(NSString *)page
{
if(![[VCSpinnerView sharedInstance] isSpinnerAddedToTheView:self.view])
[[VCSpinnerView sharedInstance] showInView:self.view];
__block __weak VCMyOrderViewController* blockMyOrderListView = self;
[[VCModelManager sharedInstance] getMyOrderDetail:[[VCConfiguration sharedConfig] getLoggedInUserId] andPageNumber:page completionBlock:^(id result, NSError *error)
{
if (!error)
{
blockMyOrderListView.orderHistoryDataObject = (OrderHistoryBaseClass *)result;
dispatch_async(dispatch_get_main_queue(), ^{
[blockMyOrderListView setDataSourceMyOrders:blockMyOrderListView.orderHistoryDataObject.rESPONSE];});
}
else
{
NSLog(#"\nError->%#",[error debugDescription]);
}
dispatch_async(dispatch_get_main_queue(), ^{
[[VCSpinnerView sharedInstance] removeSpinnerView];
});
}];
}
- (void)setDataSourceMyOrders:(OrderRESPONSE *)response
{
self.orderHistoryDataObject.rESPONSE = response;
[self setPageMark:self.orderHistoryDataObject.rESPONSE.nextCursorMark];
[self setPageCount:[self.orderHistoryDataObject.rESPONSE.totalOrderCount integerValue]];
self.arrOrderList = [NSMutableArray arrayWithArray:self.orderHistoryDataObject.rESPONSE.orderList];
TrackOrderView *trackOrderView = [[TrackOrderView alloc] init];
[trackOrderView setDelegate:self];
[self.tblMyOrder setTableHeaderView:trackOrderView];
[self.tblMyOrder reloadData];
}
2 - when scrolling the Table
- (void) scrollViewDidScroll:(UIScrollView *)scrollView
{
if (self.arrOrderList.count < self.pageCount)
{
[self ServiceCallForOrderHistoryWithCurrentPageMark:self.pageMark];
}
}

Answer 1

You need to:
Have a mutable array to store the full list
Have variable to store the next URL (or next cursor mark)
In viewDidLoad, set the mutable array to an empty array, and the URL to the initial URL
Still in viewDidLoad, call your method to load more data
This method should append the data received to your mutable array, update the URL with the next URL to call (or nil if there's no more data)
The method should call beginUpdates, then insertRowsAtIndexPaths:withRowAnimation: and then endUpdates
In scrollViewDidScroll, check the scroll offset against the size of the table and the visible size, and if you're near the end, call the method to load more data.
Of course, the method that loads additional data should exit right away when the URL to load is nil