Is this the right way to handle background thred?

Question

I do a lot of request to the server:

    NSMutableURLRequest *theRequest = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:urlString]cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:60.0];
    [theRequest setValue:@"gzip" forHTTPHeaderField:@"Accept-Encoding"]; 

     urlData = [[NSMutableData data] retain];
    urlConnection = [[NSURLConnection alloc] initWithRequest:theRequest delegate:self startImmediately:YES];

    if (urlConnection) 
    {
        finishedLoading = FALSE;
        while(!finishedLoading) {
            [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];
        }
    }
    else 
    {
        [delegate swHttpConnection:self withRequest:urlString failedWithError:nil];
    }

...When the request is done, I get a callback. However, If I use the code below, the selector won't get called:

- (void)request:(MBRequest *)request finished:(NSMutableArray *)resultArray
{
    //Handle resultArray data 

    [self performSelector:@selector(someRandomFunction) withObject: nil afterDelay:1.0f]; 
}

..but if I use the code below; It works fine:

- (void)request:(MBRequest *)request finished:(NSMutableArray *)resultArray
{
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND,0), ^(void) 
    {
        dispatch_async(dispatch_get_main_queue(), ^(void) 
        {
            //Handle resultArray data 

            [self performSelector:@selector(someRandomFunction) withObject: nil afterDelay:1.0f]; 
        }); 
    }); 
}

So my question is twofold.

Is this the right way to do it? Do I need to force the callback to be run on the mainthred, or is the logic of the code wrong?
If I do have to force the callback to be ran on the mainthred, is the code above correct?

Also, the server request code crash sometimes at the:

[[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];

And I get this warning somethings:

Class _NSZombie_NSRunLoop is implemented in both ?? and ??

Thanks in advance

Hi, thanks for response. The update function can be anything. Right now its just an empty function. I put an NSLog in it, and it never gets called — BlackMouse, Jun 02 '12 at 09:09
The "//Handle resultArray data" does it handle UI or some shared storage? — Omar Abdelhafith, Jun 02 '12 at 09:17
Yes, it updates the UI including a tableView, and update some local storage — BlackMouse, Jun 02 '12 at 09:29

score 2 · Answer 1 · answered Jun 02 '12 at 09:32

2

I don't think NSURLConnectionDelegate has a request:finished: method? and by looking at your code it seams as your using MBRequest. If so I strongly think you should have a look at their webpage for example how to do this using blocks.

answered Jun 02 '12 at 09:32

Mattias Wadman

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score 1 · Accepted Answer · answered Jun 02 '12 at 09:34

As you update the UI in this segment

  dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND,0), ^(void) 
    {
        dispatch_async(dispatch_get_main_queue(), ^(void) 
        {
            //Handle resultArray data 

            [self performSelector:@selector(someRandomFunction) withObject: nil afterDelay:1.0f]; 
        }); 
    });

then it has to be called in the UI thread then yes you have to do it

Is this the right way to handle background thred?

2 Answers2