Making stringWithContentsOfURL asynchronous - Is it safe?

Question

I attempted to make -[NSString stringWithContentsOfURL:encoding:error:] asynchronous, by running it a-synchronically from a background thread:

__block NSStri         


        

Answer 1

-(void)loadappdetails:(NSString*)appid {
    NSString* searchurl = [@"https://itunes.apple.com/lookup?id=" stringByAppendingString:appid];

    [self performSelectorInBackground:@selector(asyncload:) withObject:searchurl];

}
-(void)asyncload:(NSString*)searchurl {
    NSURL* url = [NSURL URLWithString:searchurl];
    NSError* error = nil;
    NSString* str = [NSString stringWithContentsOfURL:url encoding:NSUTF8StringEncoding error:&error];
    if (error != nil) {
        NSLog(@"Error: %@", error);
    }
    NSLog(@"str: %@", str);
}

Answer 2

You can also use:

dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);

dispatch_async(queue, ^{
        NSError *error = nil;
        NSString *searchResultString = [NSString stringWithContentsOfURL:[NSURL URLWithString:searchURL]
                                                           encoding:NSUTF8StringEncoding
                                                              error:&error];
        if (error != nil) {
            completionBlock(term,nil,error);
        }
        else
        {
            // Parse the JSON Response
            NSData *jsonData = [searchResultString dataUsingEncoding:NSUTF8StringEncoding];
            NSDictionary *searchResultsDict = [NSJSONSerialization JSONObjectWithData:jsonData
                                                                              options:kNilOptions
                                                                                error:&error];
            if(error != nil)
            {
                completionBlock(term,nil,error);
            }
            else
            {

                //Other Work here
            }
        }
    });

But yes, it should be safe. I've been told though to use NSURLConnection instead due to error calls and such when communicating via the internet. I'm still doing research into this.

Answer 3

That should be safe, but why reinvent the wheel?

NSURLRequest *req = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.google.com"]];
[NSURLConnection sendAsynchronousRequest:req queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
    NSString *result = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    // etc
}];