在nsdictionary中的块？ [英] blocks in nsdictionary?

问题描述

所以我将块动作存储到一个nsmutabledictionary，然后当响应回到websocket时回忆它们。这将异步请求转换为块语法。这里是下面的代码：

So I'm storing block actions into a nsmutabledictionary and then recalling them when a response comes back on a websocket. This turns async request into a block syntax. Here's the stripped down code:

- (void)sendMessage:(NSString*)message responseAction:(void (^)(id))responseAction
{ 
    NSString *correlationID =  (NSString*)[[message JSONValue] objectForKey:@"correlationId"];

    [self.messageBlocks setObject:responseAction forKey:correlationID];

    NSLog(@"Sending message: %@", correlationID);
   [webSocket send:message];
}

- (void)webSocket:(SRWebSocket *)wsocket didReceiveMessage:(id)message;
{
    NSString *correlationID = (NSString*)[[message JSONValue] objectForKey:@"correlationId"];
    NSLog(@"Incoming message. CorrelationID: %@", correlationID);
    void (^action)(id) = nil;
    if (correlationID) {
        action = [messageBlocks objectForKey:correlationID];
        if (action) action([message JSONValue]);
        [messageBlocks removeObjectForKey:correlationID];
    }
}

注意：服务器以发送的correlationID与请求。因此每个响应通过该id链接到每个请求。

Note: The server responds with a correlationID that is sent with the request. So each response is linked to each request through that id.

这完美的，比我预想的更好。我有的问题是，这种方式运行块是安全的吗？正在调用[messageBlocks removeObjectForKey：correlationID];足以从内存中删除它。我记得pre-ARC，block_release是一个选项。

This works perfectly, better than I expected. The question I have is that is it safe to run blocks this way? Is calling [messageBlocks removeObjectForKey:correlationID]; enough to remove it from the memory. I remember pre-ARC, block_release was an option.

推荐答案

您需要复制基于堆栈的块才能将它们安全地存储在容器中。

You need to copy stack-based blocks in order to safely store them in a container.

[self.messageBlocks setObject:[responseAction copy] forKey:correlationID];

对于非ARC代码，您需要 -autorelease it。

For non-ARC code, you need to -autorelease it also.

[self.messageBlocks setObject:[[responseAction copy] autorelease] forKey:correlationID];

希望有帮助。

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