Question

I am parsing XML that gets the first 25 items in my MySQL database using PHP – LIMIT and GET. When I click on the “Load More” cell that I append to the bottom of my tableview, it successfully gets the next 25 items, but only loads the first 40 and leaves off the last 10. Each time I click on the “Load more” cell it add 25 to my range (ie 0-25,25-50), but it seems that my range caps at 65 and the display caps at 40.

Here is my load more function thats not working:

-(void) getNewRange{
    int currentRange = [allItems count];
    int newRange = currentRange + 25;

    if(newRange > [xmlParser total]){
        NSLog(@"evaluating as greater than the total, which is 837");
        newRange = [xmlParser total];
    }

    NSString *range = [[NSString alloc] initWithFormat:@"?range=%d&range2=%d",currentRange,newRange];
    NSString *newUrl =[[NSString alloc] initWithFormat:@"http://localhost/fetchAllTitles.php%@",range];

    XMLParser *tempParser = [[XMLParser alloc] loadXMLByURL:newUrl];
    [allItems addObjectsFromArray:[tempParser people]];
    NSMutableArray *newCells = [[NSMutableArray alloc] initWithCapacity:25];

    for(int i=currentRange;i<newRange;i++){
        NSLog(@"%d",i);
         NSIndexPath *indexpath=[NSIndexPath indexPathForRow:i inSection:0];
        [newCells addObject:indexpath];
    }

    NSLog(@"%@",newUrl);

    [self.tableView insertRowsAtIndexPaths:newCells withRowAnimation:UITableViewRowAnimationAutomatic];
}

I’m getting closer, but I get this new error:

*** Assertion failure in -[_UITableViewUpdateSupport _computeRowUpdates], /SourceCache/UIKit_Sim/UIKit-1912.3/UITableViewSupport.m:386

Answer 1

UITableView isn’t a class to contain your data, and you shouldn’t try to directly micromanage what cells it displays. As another poster stated, read up on how to use it. What you should do is:

-(void)loadNewData
{
    NSIndexPath *index;
    XMLParser *tempParser = [[XMLParser alloc] loadXMLByURL:newUrl];
    NSArray *people=[tempParser people];
    for(id *person in people)
    {
        [self.dataArray addObject:person];
        indexPath=[NSIndexPath indexPathForRow:[self.dataArray indexForObject:person] inSection:0];
        [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:indexPath withRowAnimation:UITableViewRowAnimationAutomatic];
    }
}

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{ 
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return [AnArray count];//use whatever array stores your data
}


//If you've subclassed the cell, adjust appropriately.
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell=[tableView dequeueReusableCellWithIdentifier:@"cell"];
    if (!cell) {
        cell=[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"cell"];
    }
    //Customize the cell
    return cell;
}

The table view will take care of all the logic involved in displaying the cells, if you let it. This way, you only have a limited number of cells taking up memory at any given time, and you don’t have to handle that — the table view automagically handles reusing the cells, and knowing how many are needed as a buffer before / after.