Automatically load more articles in TableView - iphone

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:
How to put that extra cell in which would appear loading indicator
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

Answer 2

Q1: add 1 more cell for load more status:
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return cellsCount <= 0 ? 0 : cellsCount + 1;
}
and create load more cell:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
if (indexPath.row == cellsCount) {
if (loadMoreCell == nil) {
self.loadMoreCell = [[LoadMoreTableCell alloc] initWithStyle:UITableViewCellStyleDefault
reuseIdentifier:#"LoadMoreCellIdentifier"];
}
return loadMoreCell;
}
...
}
You can custom LoadMoreTableCell as you want.
Q2:
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
float offset = (scrollView.contentOffset.y - (scrollView.contentSize.height - scrollView.frame.size.height));
if (offset >= 0 && offset <= 5) {
[self loadMoreData];
}
}

Answer 3

I also do like this thing in my app,
Here you can use AsyncImage class which is useful to download image with url in background so your tableview scroll smooth..
here two link hope this help you for download image in background...
1.https://github.com/Koolistov/Image-Cache
2.https://github.com/rs/SDWebImage
2nd thing you want to download at bottom to another data and cell then here if you use 1 condition then its work which you like...
in cellForRowAtIndexPath tableview Delegate Method
if(indexPath.row==[yourArray count]-1){
.....do somthing which you like.....(Reload table with your json or another data)
}
here only simple logic other wise better idea is put button at your last row...
Hope this help you..
:)