管理多个异步NSURLConnection连接

问题描述

我在类中有很多重复的代码，如下所示：

I have a ton of repeating code in my class that looks like the following:

NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request
                                                              delegate:self];

异步请求的问题是当您有各种请求关闭时，将它们全部作为一个实体，大量的分支和丑陋的代码开始制定开始：

The problem with asynchronous requests is when you have various requests going off, and you have a delegate assigned to treat them all as one entity, a lot of branching and ugly code begins to formulate going:

我们得到什么样的数据？如果它包含这，做那，否则做其他。这将是有用的，我认为能够标记这些异步请求，有点像你能够标记视图与ID。

What kind of data are we getting back? If it contains this, do that, else do other. It would be useful I think to be able to tag these asynchronous requests, kind of like you're able to tag views with IDs.

我很好奇什么策略对于管理处理多个异步请求的类最有效。

I was curious what strategy is most efficient for managing a class that handles multiple asynchronous requests.

推荐答案

我跟踪由与其关联的NSURLConnection键入的CFMutableDictionaryRef中的响应。即：

I track responses in an CFMutableDictionaryRef keyed by the NSURLConnection associated with it. i.e.:

connectionToInfoMapping =
    CFDictionaryCreateMutable(
        kCFAllocatorDefault,
        0,
        &kCFTypeDictionaryKeyCallBacks,
        &kCFTypeDictionaryValueCallBacks);

这可能看起来奇怪，而不是NSMutableDictionary，但我这样做，因为这个CFDictionary只保留其键（NSURLConnection），而NSDictionary复制其键（而NSURLConnection不支持复制）。

It may seem odd to use this instead of NSMutableDictionary but I do it because this CFDictionary only retains its keys (the NSURLConnection) whereas NSDictionary copies its keys (and NSURLConnection doesn't support copying).

完成后：

CFDictionaryAddValue(
    connectionToInfoMapping,
    connection,
    [NSMutableDictionary
        dictionaryWithObject:[NSMutableData data]
        forKey:@"receivedData"]);

现在我有一个用于每个连接的数据的info字典，关于连接，并且info字典已经包含了一个可变的数据对象，我可以使用它来存储回复数据。

and now I have an "info" dictionary of data for each connection that I can use to track information about the connection and the "info" dictionary already contains a mutable data object that I can use to store the reply data as it comes in.

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    NSMutableDictionary *connectionInfo =
        CFDictionaryGetValue(connectionToInfoMapping, connection);
    [[connectionInfo objectForKey:@"receivedData"] appendData:data];
}

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