Asynchronous download issue with UITableView & ASIHTTP - iphone

Question

I try to load some image on my UITableView with ASIHTTP but I have some problems. First of all I read an xml file (with tbxml) and I save title, image path and description in a dictionary and then in an array, for parsing I use this code:
- (void)loadUnknownXML {
// Load and parse the books.xml file
tbxml = [TBXML tbxmlWithURL:[NSURL URLWithString:#"http://www.xxx.com"]];
// If TBXML found a root node, process element and iterate all children
if (tbxml.rootXMLElement){
[self traverseElement:tbxml.rootXMLElement];
}
}
- (void) traverseElement:(TBXMLElement *)element {
TBXMLElement *child = element->firstChild;
TBXMLElement *items = [TBXML childElementNamed:#"item" parentElement:child];
do{
if (items->firstChild) {
TBXMLElement *titolo = [TBXML childElementNamed:#"title" parentElement:items];
TBXMLElement *descrizione = [TBXML childElementNamed:#"description" parentElement:items];
//NSLog(#"Titolo: %# \n Descrizione: %#",[TBXML textForElement:titolo],[TBXML textForElement:descrizione]);
self.elemento = [[NSMutableDictionary alloc] init];
[self.elemento setObject:[TBXML textForElement:titolo] forKey:#"Titolo"];
NSString *indirizzoImmagine = [TBXML textForElement:descrizione];
NSRange rangeSRC = [indirizzoImmagine rangeOfString:#"src=\""];
indirizzoImmagine = [indirizzoImmagine substringFromIndex:NSMaxRange(rangeSRC)];
NSRange rangeAMP = [indirizzoImmagine rangeOfString:#"&amp"];
NSRange rangeWidth = [indirizzoImmagine rangeOfString:#"&width"];
if (rangeAMP.location != NSNotFound) {
indirizzoImmagine = [indirizzoImmagine substringToIndex:NSMaxRange(rangeAMP)];
}
else if (rangeWidth.location != NSNotFound){
indirizzoImmagine = [indirizzoImmagine substringToIndex:NSMaxRange(rangeWidth)];
}
indirizzoImmagine = [indirizzoImmagine stringByReplacingOccurrencesOfString:#"&amp" withString:#""];
indirizzoImmagine = [indirizzoImmagine stringByReplacingOccurrencesOfString:#"&width" withString:#""];
[self.elemento setObject:indirizzoImmagine forKey:#"IndirizzoImmagine"];
[self.elemento setObject:[TBXML textForElement:descrizione] forKey:#"Descrizione"];
[self.array addObject:self.elemento];
}
}
while ((items=items->nextSibling));
}
then I start with download
- (void) loadURL:(NSURL *)url index:(int)index
{
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];
ASIDownloadCache *cache = [[ASIDownloadCache alloc] init];
[request setDownloadCache:cache];
[request setCacheStoragePolicy:ASICachePermanentlyCacheStoragePolicy];
[request setCachePolicy:ASIOnlyLoadIfNotCachedCachePolicy];
[cache setStoragePath:#"/Users/kikko/kikko/xxx"];
request.userInfo = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithInt:index], #"index",
url, #"url", nil];
[request setDelegate:self];
[request startAsynchronous];
}
- (void)requestFinished:(ASIHTTPRequest *)request
{
int index = [[request.userInfo valueForKey:#"index"] intValue];
ASIDownloadCache *cache = [[ASIDownloadCache alloc] init];
[cache setStoragePath:#"/Users/kikko/kikko/xxx"];
[request.userInfo valueForKey:#"url"];
if ([cache cachedResponseDataForURL:[request.userInfo valueForKey:#"url"]]==nil) {
NSLog(#"%#",[request.userInfo valueForKey:#"url"]);
NSIndexPath* indexPath = [NSIndexPath indexPathForRow:index inSection:0];
NSArray* rows = [NSArray arrayWithObjects:indexPath, nil];
[table reloadRowsAtIndexPaths:rows withRowAnimation:UITableViewRowAnimationNone];
}
}
- (void)requestFailed:(ASIHTTPRequest *)request
{
NSError *error = [request error];
NSLog(#"Error: %#",error);
}
at the end I put the image inside cell.imageview
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return self.array.count;
}
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
return 50;
}
-(NSString *) stringByStrippingHTML:(NSString *)stringa {
NSRange r;
NSString *str = stringa;
while ((r = [str rangeOfString:#"<[^>]+>" options:NSRegularExpressionSearch]).location != NSNotFound)
str = [str stringByReplacingCharactersInRange:r withString:#""];
return str;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"ItemCell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (!cell) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
}
elemento = [array objectAtIndex:indexPath.row];
NSURL *indirizzoImmagine = [NSURL URLWithString:[elemento objectForKey:#"IndirizzoImmagine"]];
[self loadURL:indirizzoImmagine index:indexPath.row];
ASIDownloadCache *cache = [[ASIDownloadCache alloc] init];
[cache setStoragePath:#"/Users/kikko/kikko/xxx"];
dataImmagine = [cache cachedResponseDataForURL:indirizzoImmagine];
[cell.imageView setImage:[UIImage imageWithData:dataImmagine]];
cell.textLabel.text = [elemento objectForKey:#"Titolo"];
return cell;
}

Answer 1

There are a lot of ways to go about this, but the most minimally invasive way to your existing code is to attach a userinfo dictionary to your request object.
In your traverse method do this:
//...
while ((items=items->nextSibling));
for (int i = 0; i < [self.array count]; i++)
{
[arrayData addObject:[NSNull null]];
}
Then do this in your request methods
- (void) loadURL:(NSURL *)url index:(int)index
{
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];
[request setDownloadCache:[ASIDownloadCache sharedCache]];
[request setCacheStoragePolicy:ASICachePermanentlyCacheStoragePolicy];
[request setCachePolicy:ASIOnlyLoadIfNotCachedCachePolicy];
request.userInfo = [NSDictionary dictionaryWithObjectsAndKeys: [NSNumber numberWithInt:index], #"index", nil];
[request setDelegate:self];
[request startAsynchronous];
}
- (void)requestFinished:(ASIHTTPRequest *)request
{
NSData *responseData = [request responseData];
int index = [[request.userInfo valueForKey:#"index"] intValue];
[arrayData replaceObjectAtIndex:index withObject:responseData];
//EDIT below:
NSIndexPath* indexPath = [NSIndexPath indexPathForRow:index inSection:0];
NSArray* rows = [NSArray arrayWithObjects:indexPath, nil];
[self.tableView reloadRowsAtIndexPaths:rows withRowAnimation:UITableViewRowAnimationNone];
}
In your cell code, do this:
if ([arrayData objecAtIndex:indexPath.row] != [NSNull null]) {
UIImage *img = [UIImage imageWithData:[self.arrayData objectAtIndex:indexPath.row]];
imageView.image = img;
[cell.imageView setImage:img];
} else {
imageView.image = nil;
}

Answer 2

There is best example given by Apple to download and show images Asyn
https://developer.apple.com/library/ios/#samplecode/LazyTableImages/Introduction/Intro.html
Meanwhile i will check your code as well