弱自我可以在区块中间变成零吗? [英] Can __weak self turn nil in the middle of the block?

问题描述

在运行于后台线程的代码块中使用__weak self引用时，我是否仅需要在开始时检查nil，或者即使在执行过程中__weak self也可以变为nil第一个nil测试通过后执行?我想从块中的self访问一些ivars，并且在块执行时需要最新的值.

When using a __weak self reference in my block that runs on a background thread, do I only need to check for nil in the beginning, or can the __weak self become nil even during execution after the first nil test has passed? I want to access some ivars from self in the block and I need the latest values at the time the block is executing.

推荐答案

如果没有人持有对self的引用，那么可以.您可以通过在代码块中充分引用来缓解这种情况

If no one is holding a reference to self then yes. You can mitigate this by taking a strong reference in the block

__weak __typeof(self) weakSelf = self;

^{
  __strong __typeof(weakSelf) strongSelf = weakSelf;
  if (!strongSelf) {
    return;
  }
};

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