Question

I have TableView and in this TableView I’m printing articles. Now user must click in navigation bar item to update(download more articles from web over json). I want and I think that is better that when user scroll to bottom that automaticaly shows loading cell and start to loading or getting more articles from web.

My questions are next:

1. How to put that extra cell in which would appear loading indicator
2. and loading text How to automatically get more articles?

This functionality is in iphone app “App Store” but with click load more items.

Maybe is better to put button load more articles?

All examples and suggestions are welcome.

Thank’s for help

Answer 1

This one is easy it’s add an UITablecell at the end to load more items.

//
//  TableViewController.m
//  PartialTable
//
//  Created by Abizer Nasir on 07/07/2011.
//

#import "TableViewController.h"

#define kNumberOfItemsToAdd 8

@implementation TableViewController

@synthesize items;

// Mark: -
// Mark: Set up and tear down

- (id)init  {
    // New designated initialiser
    if (!(self = [super initWithStyle:UITableViewStyleGrouped])) {
        return nil; // Bail!
    }
    numberOfItemsToDisplay = kNumberOfItemsToAdd; // Show 10 items at startup
    return self;
}


- (id)initWithStyle:(UITableViewStyle)style {
    // Call out to the new designated initialiser
    return [self init];
}

- (void)dealloc {
    [items release];
    [super dealloc];
}

#pragma mark - View lifecycle

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
    // Return YES for supported orientations
    return (interfaceOrientation == UIInterfaceOrientationPortrait);
}

#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    if (numberOfItemsToDisplay == [items count]) {
        return 1;
    }
    return 2;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    if (section == 0) {
        return numberOfItemsToDisplay;
    } else {
        return 1;
    }
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    static NSString *CellIdentifier = @"ItemCell";

    // If the indexPath is less than the numberOfItemsToDisplay, configure and return a normal cell,
    // otherwise, replace it with a button cell.

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (!cell) {
        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
    }

    if (indexPath.section == 0) {            
        cell.textLabel.text = [items objectAtIndex:indexPath.row];
        cell.textLabel.textAlignment = UITextAlignmentLeft;        
        cell.textLabel.textColor = [UIColor blackColor];
        cell.textLabel.font = [UIFont boldSystemFontOfSize:17.f];

    } else {
        cell.textLabel.text = [NSString stringWithFormat:NSLocalizedString(@"Next %d items", @"The text to display to load more content"), kNumberOfItemsToAdd];
        cell.textLabel.textAlignment = UITextAlignmentCenter;
        cell.textLabel.textColor = [UIColor colorWithRed:0.196f green:0.3098f blue:0.52f alpha:1.f];
        cell.textLabel.font = [UIFont boldSystemFontOfSize:14.f];
    }

    return cell;
}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
    if (indexPath.section == 1) {
        NSUInteger i, totalNumberOfItems = [items count];        
        NSUInteger newNumberOfItemsToDisplay = MIN(totalNumberOfItems, numberOfItemsToDisplay + kNumberOfItemsToAdd);
        NSMutableArray *indexPaths = [[NSMutableArray alloc] init];        

        for (i=numberOfItemsToDisplay; i<newNumberOfItemsToDisplay; i++) {
            [indexPaths addObject:[NSIndexPath indexPathForRow:i inSection:0]];
        }        

        numberOfItemsToDisplay = newNumberOfItemsToDisplay;                

        [tableView beginUpdates];
        [tableView insertRowsAtIndexPaths:indexPaths withRowAnimation:UITableViewRowAnimationTop];
        [indexPaths release];                
        if (numberOfItemsToDisplay == totalNumberOfItems) {
            [tableView deleteSections:[NSIndexSet indexSetWithIndex:1] withRowAnimation:UITableViewRowAnimationTop];
        }        
        [tableView endUpdates];
        // Scroll the cell to the top of the table
        if (newNumberOfItemsToDisplay < totalNumberOfItems) {
            dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 200000000), dispatch_get_main_queue(), ^(void){
                [tableView scrollToRowAtIndexPath:indexPath atScrollPosition:UITableViewScrollPositionTop animated:YES];
            });
            [tableView deselectRowAtIndexPath:indexPath animated:YES];
        } else {
            dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 200000000), dispatch_get_main_queue(), ^(void){
                [tableView scrollToRowAtIndexPath:[NSIndexPath indexPathForRow:totalNumberOfItems-1 inSection:0] atScrollPosition:UITableViewScrollPositionTop animated:YES];
            });
        }

    }    
}

@end