如何同步使用AFNetworking 2.0库？

Question

使用AFNetworking 2.0下面的代码是有效的，通过互联网来获取数据：

NSString *URLPath = @"http://www.raywenderlich.com/downloads/weather_sample/weather.php?format=json"; 
NSDictionary *parameters = nil; 

[[AFHTTPRequestOperationManager manager] GET:URLPath parameters:parameters success:^(AFHTTPRequestOperation *operation, id responseObject) { 
    NSLog(@"success: %@", responseObject); 

} failure:^(AFHTTPRequestOperation *operation, NSError *error) { 
    NSLog(@"failure: %@", error); 
}]; 

但我想在单元测试同步测试这些请求。

// This code would be blocked. 
dispatch_semaphore_t sema = dispatch_semaphore_create(0); 

NSString *URLPath = @"http://www.raywenderlich.com/downloads/weather_sample/weather.php?format=json"; 
NSDictionary *parameters = nil; 

[[AFHTTPRequestOperationManager manager] GET:URLPath parameters:parameters success:^(AFHTTPRequestOperation *operation, id responseObject) { 
    NSLog(@"success: %@", responseObject); 
    dispatch_semaphore_signal(sema); 

} failure:^(AFHTTPRequestOperation *operation, NSError *error) { 
    NSLog(@"failure: %@", error); 
    dispatch_semaphore_signal(sema); 

}]; 

dispatch_semaphore_wait(sema, DISPATCH_TIME_FOREVER); 
dispatch_release_ARC_compatible(sema); 

我如何可以获取使用AFNetworking 2.0库同步数据（测试中Kiwi这些代码）：但是，如果使用这样当GCD信号受阻？

Answer 1

您的信号量将被阻止，因为默认情况下AFNetworking在主循环上运行。所以如果你在等待信号量的主循环，AFNetworking的代码永远不会运行。

为了解决这个问题，你只需告诉AFNetworking使用不同的调度队列。你这样做，通过设置AFHTTPRequestOperationManager

您可以创建自己的调度队列，或使用预定义者之一的operationQueue财产，像这样：

// Make sure that the callbacks are not called from the main queue, otherwise we would deadlock 
manager.operationQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);