Question

I have some code that sends multiple ASIHTTPRequests to upload and download data in a view controller. When the view controller gets dealloc’d it should clean up all unfinished requests by setting the delegate to nil.

- (void)viewDidLoad
{
        // send multiple requests
        [self sendRequest:someURL];
        [self sendRequest:someURL];
        [self sendRequest:someURL];
        [self sendRequest:someURL];
}

- (void)sendRequest:(NSString*)url
{
        ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];
        [request setDelegate:self]; 

        ASINetworkQueue *requestQueue = [ASINetworkQueue queue];
        [requestQueue setMaxConcurrentOperationCount:2];
        [requestQueue setDelegate:self];
        [requestQueue addOperation:request];
        [requestQueue go];
}

- (void)dealloc
{
    NSLog(@"cancel all operations");
    for (ASIHTTPRequest *req in ASIHTTPRequest.sharedQueue.operations)
    {
        [req cancel];
        [req setDelegate:nil];
    }

    [super dealloc];
}

However, if I pop this view controller before all operations have finished, I get a “message sent to deallocated instance” in ASIHTTPRequest.m complaining that the delegate went away in the code below.

/* ALWAYS CALLED ON MAIN THREAD! */
- (void)reportFailure
{
    ***crash here --> if (delegate && [delegate respondsToSelector:didFailSelector]) {
        [delegate performSelector:didFailSelector withObject:self];
    }
    if (queue && [queue respondsToSelector:@selector(requestFailed:)]) {
        [queue performSelector:@selector(requestFailed:) withObject:self];
    }
    #if NS_BLOCKS_AVAILABLE
    if(failureBlock){
        failureBlock();
    }
    #endif
}

How can I work around this?

Answer 1

You’re creating a new queue for each request around this line of code:

ASINetworkQueue *requestQueue = [ASINetworkQueue queue];

So the loop here won’t loop over the requests as it’s looping over the sharedQueue, not the new one(s) you’ve created:

for (ASIHTTPRequest *req in ASIHTTPRequest.sharedQueue.operations)

Requests would only get added to the sharedQueue if you use [request startAynchronous] without explicitly setting a different queue.