Caching images downloaded from the web

[JavaWizKid]

I've been looking around the web to find some simple tutorials that explain how to download an image from the internet, cache it and then put it into a uitableview when it has finished. There are some overly complicated ones on the Apple Developer website and from them I have no idea what I'm looking for.

What I have at the moment is:

	for(int i=0;i<[ImageXX count];i++)
	{
		TFHppleElement *ImageX = [ImageXX objectAtIndex:i];
		NSString *Image = [ImageX content];
		[imageArray addObject:Image];
	}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    
    static NSString *CellIdentifier = @"Cell";
    
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
    }
    
    // Configure the cell...
	NSUInteger row = [indexPath row];
	cell.font=[UIFont fontWithName:@"Helvetica" size:15.0];
	cell.textLabel.text = [Array objectAtIndex:row];
	
	NSURL *url = [NSURL URLWithString:[imageArray objectAtIndex:row]];
	NSData *imageData = [NSData dataWithContentsOfURL:url];
	UIImage* imageView = [UIImage imageWithData:imageData];
	[cell setImage: imageView];
    
    return cell;
}

Of course doing it this way makes the scrolling completely laggy as the images get downloaded every time the cell with the image is visible. Using "imageNamed:" automatically caches the images except they have to be local. Can anyone point me to a nice straight forward example how to do it asynchronously or just cache the images as they download? Thanks

[baja_yu]

It's actually very simple

NSFileManager *fileManager = [[NSFileManager alloc] init];
[fileManager createFileAtPath:localFilePath contents:[NSData dataWithContentsOfURL:[NSURL URLWithString:remoteFilePath]] attributes:nil];

localFilePath and remoteFilePath are NSStrings with paths. Local is where you want to save it (you'd probably want to save to apps Documents director), remote is a URL.

To avoid the lag you need to download and save them with the code above, then use them in the table view with the local file.

[Duncan C]

Originally Posted by baja_yu

It's actually very simple

NSFileManager *fileManager = [[NSFileManager alloc] init];
[fileManager createFileAtPath:localFilePath contents:[NSData dataWithContentsOfURL:[NSURL URLWithString:remoteFilePath]] attributes:nil];

localFilePath and remoteFilePath are NSStrings with paths. Local is where you want to save it (you'd probably want to save to apps Documents director), remote is a URL.

To avoid the lag you need to download and save them with the code above, then use them in the table view with the local file.

The code above is still doing synchronous downloads. The only way that would yield smooth downloads is if you downloaded all the images before displaying the table view.

You should implement an async download manager. There are several tutorials online on how to do this. Here's one:

UITables with Downloaded Images – Easy Asynchronous Code | markjnet