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copied!<p>There are two ways of fixing your problem:</p> <h3>The easy way out</h3> <p>is — as Dean suggests — using <code>+[NSURLConnection sendSynchronousRequest:returningResponse:error:]</code>, as you already are on a different thread. This has you covered — I'd say — 80-90% of the time, is really simple to implement and Just Works™.</p> <h3>The other way</h3> <p>is only slightly more complicated and has you covered for all the cases where the first method does not suffice — by visiting the root of your problem:</p> <p><code>NSURLConnection</code> works in conjunction with the runloop — and the threads managed by <code>NSOperationQueue</code> don't necessarily use (or even have!) an associated runloop.</p> <p>While calling <code>+[NSURLConnection connectionWithRequest:delegate:]</code> will implicitly create a runloop, if needed, <strong>it does not cause the runloop to actually run!</strong></p> <p><strong>This is your responsibility</strong>, when the <code>NSOperationQueue</code> you use is not the queue associated with the main thread.</p> <p>To do so, change your implementation of <code>fetchXMLWithCompletionHandler:</code> to look similar to the following:</p> <pre><code>- (void)fetchXMLWithCompletionHandler:(WAFetchXMLHandler)block { self.xmlHandler = block; // Declare a @property for the block with the copy attribute set self.mutableXMLData = [NSMutableData data]; // again, you should have a property for this... self.currentConnection = [NSURLConnection connectionWithRequest:request delegate:self]; // having a @property for the connection allows you to cancel it, if needed. self.connectionShouldBeRunning = YES; // ...and have a BOOL like this one, setting it to NO in connectionDidFinishLoad: and connection:didFailWithError: NSRunLoop *loop = [NSRunLoop currentRunLoop]; NSDate *neverExpire = [NSDate distantFuture]; BOOL runLoopDidIterateRegularly = YES; while( self.connectionShouldBeRunning && runLoopDidIterateRegularly ) { runLoopDidIterateRegularly = [loop runMode:NSDefaultRunLoopMode beforeDate:neverExpire]; } } </code></pre> <p>With these small changes, you're good to go. Bonus: this is really flexible and (eventually) reusable throughout all your code — if you move the XML-parsing out of that class and make your handler simply take an <code>NSData</code>, an <code>NSError</code> and (optionally) an <code>NSURLResponse</code>.</p> <p>Since you probably don't want the clients of your loader to see and possibly mess with the properties I just suggested you should add, you can declare them in a class continuation.</p>

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