Question

如何将局部块变量offDownloadBlock用于NSOperationQueue的addOperationWithBlock方法？

void (^offDownloadBlock)(NSString*, NSDictionary*);
offDownloadBlock = ^(NSString* key, NSDictionary* obj) {...};

NSOperationQueue *q = [[NSOperationQueue alloc] init];
[q addOperationWithBlock:offDownloadBlock(key, obj)];

Answer 1

没有理由这样做。 NSOperationQueue的-addOperationWithBlock：定义为- (void)addOperationWithBlock:(void (^)(void))block，这意味着该块不带任何参数并且不返回任何内容。您可以在代码中使用它，如下所示：

NSString *key = @"Some key";
NSDictionary *obj = // Some dictionary;
[q addOperationWithBlock:^(){
    // your code goes here
    // use your key and obj here to do something that will run on the queue
}];

编辑注释：如果要创建递归块，则必须在块内调用块。做这种事情的唯一方法是像这样定义你的块：

__block void (^myBlock)();
myBlock = ^(){
    NSLog(@"Running"); // This will run forever
    myBlock();
};
myBlock();

我会说这可能不是你想要做的事情，但几乎无论如何。

NSOperationQueue的addOperationWithBlock的局部块变量

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