gistfile1.m

@implementation DTProgressReportingURLProtocol
{
  NSURLConnection *_connection;
	
	dispatch_semaphore_t _semaphore;
}

+ (BOOL)canInitWithRequest:(NSURLRequest *)request
{
	NSLog(@"%@", [self propertyForKey:@"UserAgentSet" inRequest:request]);
	
	if ([[self propertyForKey:@"UserAgentSet" inRequest:request] boolValue])
	{
		return NO;
	}
	
	return YES;
}

+ (NSURLRequest *)canonicalRequestForRequest:(NSURLRequest *)request
{
	return request;
}

+ (BOOL)requestIsCacheEquivalent:(NSURLRequest *)a
                       toRequest:(NSURLRequest *)b
{
	return [a.URL isEqual:b.URL];
}


- (void)startLoading
{
	NSLog(@"%s %@", __PRETTY_FUNCTION__, self.request.URL);
	
	NSMutableURLRequest *mutableRequest = [self.request mutableCopy];
	[NSURLProtocol setProperty:@YES forKey:@"UserAgentSet" inRequest:mutableRequest];
	
	_semaphore = dispatch_semaphore_create(0);
	
	dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0), ^{
		// startNext downloading
		_connection = [[NSURLConnection alloc] initWithRequest:mutableRequest delegate:self startImmediately:NO];
		
		// without this special it would get paused during scrolling of scroll views
		[_connection scheduleInRunLoop:[NSRunLoop mainRunLoop] forMode:NSRunLoopCommonModes];
		
		//[_connection setDelegateQueue:[NSOperationQueue mainQueue]];
		[_connection start];
	});
	
	
	dispatch_semaphore_wait(_semaphore, DISPATCH_TIME_FOREVER);
}

- (void)stopLoading
{
	NSLog(@"%s %@", __PRETTY_FUNCTION__, self.request.URL);
	
	[_connection cancel];
	_connection = nil;
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
	NSLog(@"%s %@", __PRETTY_FUNCTION__, self.request.URL);
	[self.client URLProtocol:self didLoadData:data];
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
	NSLog(@"%s %@", __PRETTY_FUNCTION__, self.request.URL);
	[self.client URLProtocol:self didFailWithError:error];
	_connection = nil;
	
	dispatch_semaphore_signal(_semaphore);

}

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
	NSLog(@"%s %@", __PRETTY_FUNCTION__, self.request.URL);
	[self.client URLProtocol:self didReceiveResponse:response cacheStoragePolicy:NSURLCacheStorageAllowed];
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
	NSLog(@"%s %@", __PRETTY_FUNCTION__, self.request.URL);
	[self.client URLProtocolDidFinishLoading:self];
	_connection = nil;
	
	dispatch_semaphore_signal(_semaphore);
}

@end