在这里，我试图在GCD中调用我的ASIHTTP请求.但是Completion块和failed块没有执行

Question

这里我试图在GCD中调用我的ASIHTTPRequest。有时，完成块和失败块没有执行。我想做的是，在这个请求完成后，我必须在另一个ASIHTTPRequest中使用返回的数据。那么如何改进这段代码呢:

 ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:[NSURL URLWithString:url]];
    [request setCompletionBlock:^{
        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0), ^{
            NSData *_responseData = [request responseData];
            NSString *response = [[NSString alloc] initWithData:_responseData encoding:NSASCIIStringEncoding] ;
            self.albumDic = [response JSONValue];
            [response release];
            dispatch_async(dispatch_get_main_queue(), ^{
                [self GetDictionary:self.albumDic];
            });
        });
    }];
    [request setFailedBlock:^{
        NSError *error = [request error];
        NSLog(@"Error : %@", error.localizedDescription);
    }];
    [request startSynchronous];

Answer 1

别那样。你在线程上做线程(GCD使用线程，异步使用ashttprequest也是如此)。

使用ASINetworkQueue代替-阅读这里

这里有一个简单的用法:

- (void)addRequestsToNetworkQueue:(NSArray *)requests {    
// Stop anything already in the queue before removing it
[[self networkQueue] cancelAllOperations];
// Creating a new queue each time we use it means we don't have to worry about clearing delegates or resetting progress tracking
[self setNetworkQueue:[ASINetworkQueue queue]];
[[self networkQueue] setDelegate:self];
[[self networkQueue] setRequestDidFinishSelector:@selector(requestFinished:)];
[[self networkQueue] setRequestDidFailSelector:@selector(requestFailed:)];
[[self networkQueue] setQueueDidFinishSelector:@selector(queueFinished:)];
//Add all requests to queue
for (ASIHTTPRequest *req in requests) {
    [[self networkQueue] addOperation:req];
}
//Start queue 
[[self networkQueue] go];
}

ASINetworkQueue提供了许多委托方法(大多数也是可定制的)，因此您可以在请求完成时更新GUI等等。它是异步的，所以GCD是不必要的。