Swift 闭包中 'weak self' 的 Objective-C 等价物是什么？

What is the Objective-C equivalent of 'weak self' in a Swift closure?

你能告诉我相当于：

var didTapURL: ((_ url: URL) -> Void)?

..........

myObject.didTapURL = { [weak self] (url) in
     self?.manageUrl(url)
}

在 Objective-C 中？

是__weak，见下文

__weak __typeof(self) weakSelf = self;

// ...

    dispatch_async(dispatch_get_main_queue(), ^{
      [weakSelf call_some_selector];
    });