Check if NSURL returns 404

Question

I need to check whether a URL (represented by a NSURL) is available or returns 404. What is the best way to achieve that?

I would prefer a way to check this without a delegate, if possible. I need to block the program execution until I know if the URL is reachable or not.

Answer 1

As you may know already that general error can capture by didFailWithError method:

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {     NSLog(@"Connection failed! Error - %@ %@",           [error localizedDescription],           [[error userInfo] objectForKey:NSErrorFailingURLStringKey]); } 

but for 404 "Not Found" or 500 "Internal Server Error" should able to capture inside didReceiveResponse method:

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {     if ([response respondsToSelector:@selector(statusCode)])     {         int statusCode = [((NSHTTPURLResponse *)response) statusCode];         if (statusCode == 404)         {             [connection cancel];  // stop connecting; no more delegate messages             NSLog(@"didReceiveResponse statusCode with %i", statusCode);         }     } } 

Answer 2

I needed a solution that didn't use a delegate either, so I took pieces of code shown in other answers here and created a simple method that works well in my case (and might be what you are looking for as well):

    -(BOOL) webFileExists {          NSString *url = @"http://www.apple.com/somefile.html";          NSURLRequest* request = [NSURLRequest requestWithURL:[NSURL URLWithString:url] cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:5.0];         NSHTTPURLResponse* response = nil;         NSError* error = nil;         [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];         NSLog(@"statusCode = %d", [response statusCode]);          if ([response statusCode] == 404)             return NO;         else             return YES;      }