NSOperationQueue addOperationWithBlock with return in iOS - objective-c

Question

I have written method -(void) getStatus:(NSString*) url with return type,
-(NSString) getStatus:(NSString*) statusUrl
{
NSURL *urlObj = [NSURL URLWithString:[statusUrl
stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
NSError *err;
NSString *response = [NSString stringWithContentsOfURL: urlObj encoding:
NSUTF8StringEncoding error:&err];
return response;
}
But stringWithContentsOfURL is performing operation in main Thread, So while calling this method application struck for a second.
So I need to perform stringWithContentsOfURL function in background thread and after getting the response i want to return the response.
My current code:
-(NSString) getStatus:(NSString*) statusUrl
{
NSURL *urlObj = [NSURL URLWithString:[statusUrl
stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
NSError *err;
NSOperationQueue *rbQueue = [[[NSOperationQueue alloc] init] autorelease];
[rbQueue addOperationWithBlock:^{
NSString *response = [NSString stringWithContentsOfURL: urlObj
encoding: NSUTF8StringEncoding error:&err];
[[NSOperationQueue mainQueue] addOperationWithBlock:^{
return response;
}];
}];
return #"";
}
But now me receiving a empty string #"", I can not receive response i got from server. Is there any way to do the same task..

Answer 1

Have you noticed that there should be some changes with this approach to complete the task? You hardly can use getters this way because of the nature of asynchronous methods. Or the getters will block the main thread in their turn.
To avoid this I could recommend you to use NSNotification to update the UI after you complete the server request in the background thread;
or change your getter method definition to pass the result from the background thread to the main thread, but asynchronously:
- (void)getStatusAsychronously:(NSString *)statusUrl withCompletionBlock:(void(^)(NSString *result))completionBlock;
or even consider subclassing NSOperation object for server request. The NSOperation subclasses are really handy with NSOperationQueue instances and could provide some more useful features like the cancellation of operation.