Fetching Remote Images

gistfile1.m

dispatch_queue_t img_queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_async(img_queue, ^{
 
    NSURL *url = [NSURL URLWithString:@"http://imgs.xkcd.com/comics/formal_logic.png"];
    NSError *error = nil;
    NSData *image = [NSData dataWithContentsOfURL:url options:0 error:&error];
 
    if(!error && image && [image length] > 0) {
        NSArray *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
        NSString *path = [[paths objectAtIndex:0] stringByAppendingPathComponent:@"image.png"];
 
        [image writeToFile:path options:0 error:&error];
    }
UIImage *img = [UIImage imageWithData:image];