广播“弱自我”到逃避块

Question

如果捕获规则位于我们将某个弱捕获的对象（例如self）广播到下一个转义块的某个块内，则该捕获规则如何工作？

myBlock = { [weak self] in
    ...
    nextBlock() { [weak self] in // is it necessary if `weak self` already captured in parent block?
        ...
    }
}

如果我们不在子块中写[weak self]，self会被强捕获还是保持弱势？