IOS TableView远程图片加载笔记

//
//  SwwTableViewController.m
//  tableviewdemo
//
//  Created by hundsun on 14-9-14.
//  Copyright (c) 2014年 Robinson_911. All rights reserved.
//  本人博客地址： http://blog.csdn.net/robinson_911 
#import "SwwTableViewController.h"
#import "SwwTableViewCell.h"
#import "DownloadHelper.h"

@interface SwwTableViewController ()
-(void)startIconDownload:(SwwTableViewCell*) shopdata forIndexPath:(NSIndexPath*) indexPath;
@end

@implementation SwwTableViewController

@synthesize myArray;
@synthesize items;
@synthesize imageDownloadProgress;
NSString *books;
NSString *prices;
-(void) loadJsonData:(NSURL *)url
{
NSURLRequest *request = [NSURLRequest requestWithURL:url];
DownloadHelper *help = [[DownloadHelper alloc] initWithRequest:request];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(parseJsonData:) name:@"connectionFinished" object:help];
[[help connection] start];
}

-(void) parseJsonData:(NSNotification *)n
{
items = [[NSMutableArray alloc]initWithCapacity:0];
DownloadHelper* help = [n object];
NSData *data = [help receivedData];
NSError *error;
NSArray *json = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&error];
if (json == nil) {
NSLog(@"json parse failed \r\n");
return;
}

for (int i=0; i < [json count]; i++) {
NSArray *s = [json objectAtIndex:i];
SwwTableViewCell *shopdata = [[SwwTableViewCell alloc] init];
shopdata.text1= [s objectAtIndex:1];
shopdata.text2 = [s objectAtIndex:3];
shopdata.text3 = [s objectAtIndex:0];
shopdata.url = [s objectAtIndex:2];
[self.myArray addObject:shopdata];
[shopdata release];
}
[self.tableView reloadData];
}

- (id)initWithStyle:(UITableViewStyle)style
{
self = [super initWithStyle:style];
if (self) {
}
return self;
}

- (void)viewDidLoad
{

self.myArray = [NSMutableArray array];
NSURL *url = [NSURL URLWithString:kDoubanUrl];
[self loadJsonData:url];
self.tableView.dataSource = self;
self.tableView.delegate = self;

[super viewDidLoad];
}

- (void)viewDidUnload
{
[super viewDidUnload];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}

#pragma mark - Table view data source
/*
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
#warning Potentially incomplete method implementation.
// Return the number of sections.
return 2;

}*/

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
// Return the number of rows in the section.
return [myArray count];
}

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

SwwTableViewCell *cells = [tableView dequeueReusableCellWithIdentifier:TableViewDynamicLoadIdentifier];
if (cells == nil)
{
cells = [[[SwwTableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle
reuseIdentifier:TableViewDynamicLoadIdentifier]autorelease] ;
cells.selectionStyle = UITableViewCellSelectionStyleNone;
}

//   cells.parent=self;
//  cells.label1.text = @"55元" ;
//  cells.label2.text = @"邓小平" ;
// [cells setCell];
// return cells;

//   NSLog(@"%@",dic);
//   NSLog(@"%@",cells.dic);

NSInteger nRow = [indexPath row];
SwwTableViewCell *shopdata = [self.myArray objectAtIndex:nRow];

cells.label1.text = shopdata.text1;
cells.label2.text = shopdata.text2;

if (shopdata.appIcon) {
cells.imageView.image = shopdata.appIcon;
}else{
if (self.tableView.dragging == NO && self.tableView.decelerating == NO)
{
[self startIconDownload:shopdata forIndexPath:indexPath];
}

cells.imageView.image = [UIImage imageNamed:@"Placeholder"];
}

return cells;
}

-(void)startIconDownload:(SwwTableViewCell *)shopdata forIndexPath:(NSIndexPath *)indexPath{
IconDownloader *iconDownloader = [imageDownloadProgress objectForKey:indexPath];
NSLog(@"startIconDownload iconDownloader=%@",iconDownloader);
if (iconDownloader == nil)
{
iconDownloader = [[IconDownloader alloc] init];
iconDownloader.appRecord = shopdata;
iconDownloader.indexPathInTableView = indexPath;
iconDownloader.delegate = self;
[imageDownloadProgress setObject:iconDownloader forKey:indexPath];
[iconDownloader startDownload];
[iconDownloader release];
}
}

-(void)appImageDidLoad:(NSIndexPath *)indexPath{
IconDownloader *iconDownloader = [imageDownloadProgress objectForKey:indexPath];
if (iconDownloader != nil)
{
UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:iconDownloader.indexPathInTableView];

// Display the newly loaded image
cell.imageView.image = iconDownloader.appRecord.appIcon;
}

}

// this method is used in case the user scrolled into a set of cells that don't have their app icons yet
- (void)loadImagesForOnscreenRows
{
if ([self.myArray count] > 0)
{
NSArray *visiblePaths = [self.tableView indexPathsForVisibleRows];
for (NSIndexPath *indexPath in visiblePaths)
{
SwwTableViewCell *shopdata = [self.myArray objectAtIndex:[indexPath row]];

if (!shopdata.appIcon)
{
NSLog(@"start download nrow=%d",[indexPath row]);
[self startIconDownload:shopdata forIndexPath:indexPath];
}
}
}
}

- (CGFloat) tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath{
return 60;

}

-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
NSString *titileString = [NSString stringWithFormat:@"你点击了按钮%d",[indexPath row]];
UIAlertView *alert = [[ UIAlertView alloc]initWithTitle:@"提示" message:titileString delegate:self    cancelButtonTitle:@"OK"otherButtonTitles: nil];
[alert show];
int rownum = [indexPath row];
NSLog(@"===row=%d",rownum);
}
/*
// Override to support conditional editing of the table view.
- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath
{
// Return NO if you do not want the specified item to be editable.
return YES;
}
*/

/*
// Override to support editing the table view.
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
if (editingStyle == UITableViewCellEditingStyleDelete) {
// Delete the row from the data source
[tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];
} else if (editingStyle == UITableViewCellEditingStyleInsert) {
// Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view
}
}
*/

/*
// Override to support rearranging the table view.
- (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath
{
}
*/

/*
// Override to support conditional rearranging of the table view.
- (BOOL)tableView:(UITableView *)tableView canMoveRowAtIndexPath:(NSIndexPath *)indexPath
{
// Return NO if you do not want the item to be re-orderable.
return YES;
}
*/

/*
#pragma mark - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
// Get the new view controller using [segue destinationViewController].
// Pass the selected object to the new view controller.
}
*/

#pragma mark -
#pragma mark Deferred image loading (UIScrollViewDelegate)

// Load images for all onscreen rows when scrolling is finished
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
{
if (!decelerate)
{
[self loadImagesForOnscreenRows];
}
}

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
[self loadImagesForOnscreenRows];
}
@end