将块保留在字典中 [英] Keep blocks inside a dictionary
问题描述
我有自己的方法，将块作为参数。我想跟踪NSDictionary中的那个块。将块添加到字典的最佳方法是什么？
I have my own method that takes a block as an argument. I want to keep track of that block inside an NSDictionary. What is the best way to add the block to the dictionary?
我尝试了这段代码，但在执行下面的行（setObject ...）后，字典仍为空。我认为这是因为该块不是NSObject类型。但是这样做的正确方法是什么？
I tried this code but after executing the line below (setObject...) the dictionary is still empty. I presume that is because the block is not of type NSObject. But what is the right way to do this?
- (void)startSomething:(NSURLRequest*)request block:(void (^)(NSURLResponse*, NSData*, NSError*))handler {
NSURLConnection *connection = [NSURLConnection connectionWithRequest:request delegate:self];
[pendingRequests setObject:handler forKey:connection];
}
编辑：
没关系。我不知道我在想什么。 3分：
Never mind. I don't know what I was thinking. 3 points:
- 块是objc对象
- 错误：setObject应该是setValue
- forKey是一个字符串所以它应该是[连接描述]或类似的东西
无论如何我修复了我的问题现在是这样的：
Anyway I fixed my problem now like this:
- (void)startSomething:(NSURLRequest*)request block:(void (^)(NSURLResponse*, NSData*, NSError*))handler {
NSURLConnection *connection = [NSURLConnection connectionWithRequest:request delegate:self];
[pendingRequests setValue:handler forKey:[connection description]];
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^(void) {
void (^handler)(NSURLResponse*, NSData*, NSError*);
handler = [pendingRequests valueForKey:[connection description]];
handler(nil, nil, nil);
});
}
推荐答案
那仍然没有去工作，或者最多，只会巧合地工作。
That still isn't going to work or, at best, will only work coincidentally.
你需要复制处理程序然后才能将其推入词典。类似于：
You need to copy the handler before shoving it in the dictionary. Something like:
void (^handlerCopy)(NSURLResponse*, NSData*, NSError*) = Block_copy(handler);
[dict setObject:handlerCopy forKey:@"foo"];
Block_release(handlerCopy); // dict will -retain/-release, this balances the copy.
而且，是的，它应该是 setObject：forKey：和 objectForKey：。
And, yes, it should be setObject:forKey: and objectForKey:.
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