问在NSURLProtocol中的startLoading内部单独调用

EN

+canInitWithRequest(){
   if(self.request.valueForKey("handledKey") != nil){
      return false;
   }
   return true;
}

-startLoading(){

   __block NSString * realURLString = self.request.URL.absoluteString;

   //send separate http call for validation

   NSMutableURLRequest validationRequest = [NSMutableURLRequest initWithURL:[URL initWithString:OUR_VALIDATION_SERVER_URL]];

   {code to fill info into validationRequest, etc.}   

   semaphore = dispatch_semaphore_create(0); // need to sync to make sure we use the expected/real url
   [NSURLProtocol setValue:YES forkey:"handledKey" inRequest: validationRequest];
   [NSURLSession sendAsyncRequest:validationRequest ...completionHandler(response, data, error){
            realURLString = xxxx;
            print(current thread info);// line 1
       dispatch_semaphore_signal(sema);
   }];
   print(current thread info);// line 2
   dispatch_semaphore_wait(sema);

  //continue original request with real url
  NSMutableURLRequest realRequest = NSMutableURLRequest(realURLString);
  [NSURLProtocol setValue:YES forkey:"handledKey" inRequest: realRequest];
  self.connection = [NSURLSession withRequst:realRequest delegate:self];
}

}