管理多个异步 NSURLConnection 连接 [英] Managing multiple asynchronous NSURLConnection connections

问题描述

我的班级中有大量重复代码，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];

异步请求的问题在于，当您发出各种请求，并且分配了一个委托来将它们全部视为一个实体时，就会开始编写大量分支和丑陋的代码:

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:

我们要返回什么样的数据?如果它包含这个，做那个，否则做其他.我认为能够标记这些异步请求会很有用，就像您能够使用 ID 标记视图一样.

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.

我很好奇管理处理多个异步请求的类最有效的策略是什么.

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

推荐答案

我跟踪 CFMutableDictionaryRef 中的响应，该 CFMutableDictionaryRef 由与其关联的 NSURLConnection 键控.即:

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

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

使用它而不是 NSMutableDictionary 似乎很奇怪，但我这样做是因为这个 CFDictionary 只保留它的键(NSURLConnection)而 NSDictionary 复制它的键(并且 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).

一旦完成:

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

现在我有每个连接的信息"数据字典，我可以用它来跟踪有关连接的信息，信息"字典已经包含一个可变数据对象，我可以用它来存储回复数据进来了.

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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