如何通过间接传递（和设置）非对象？
NSError 对象经常像这样使用（取自 这之前问题）：
- (id)doStuff:(id)withAnotherObjc error:(NSError **)error;
我想通过 BOOL 间接实现类似的目标：
- (id)doStuff:(id)withAnotherObjc andExtraBoolResult:(BOOL **)extraBool;
但我不知道如何让它正常工作。
对于涉及 NSError 的给定方法规范，正确的实现将涉及类似的内容（同样来自 上一个问题）：
*error = [NSError errorWithDomain:...];
通过类似的逻辑，似乎这应该适用于 BOOL 间接：
*extraBool = &YES; // ERROR! Address expression must be an lvalue or a function designator
为什么这不起作用以及实现此目的的正确方法是什么？
NSError objects are frequently used like this (taken from this previous question):
- (id)doStuff:(id)withAnotherObjc error:(NSError **)error;
I want to achieve something similar with BOOL indirection:
- (id)doStuff:(id)withAnotherObjc andExtraBoolResult:(BOOL **)extraBool;
But I can't figure out how to get this working correctly.
For the given method specification involving NSError, the proper implementation would involve something like (again from the previous question):
*error = [NSError errorWithDomain:...];
With similar logic, it seems like this should work with BOOL indirection:
*extraBool = &YES; // ERROR! Address expression must be an lvalue or a function designator
Why doesn't this work and what is the proper way to implement this?
如果你对这篇内容有疑问，欢迎到本站社区发帖提问 参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。
绑定邮箱获取回复消息
由于您还没有绑定你的真实邮箱，如果其他用户或者作者回复了您的评论，将不能在第一时间通知您！
发布评论
评论（1）
请记住，对于对象，您正在使用指针（例如，
NSError*），因此使用此方法，您最终会得到一个指向指针的指针（例如，NSError* *）。但是，在使用BOOL时，您应该使用指向 BOOL 的指针：也就是说，只有一层间接寻址，而不是两层。因此，您的意思是：然后：
Keep in mind that with objects, you're working with a pointer (e.g.,
NSError*), so using this method, you wind up with a pointer to a pointer (e.g.,NSError**). When working with aBOOL, though, you should use a pointer to a BOOL: that is, only one level of indirection, not two. Therefore, you mean:and subsequently: