objective-c - ARC 不允许将间接指针转换为指向 'CFReadStreamRef *' 的 Objective-C 指针

Question

我想将 CFStreamCreatePairWithSocketToHost 与 NSInput 和 OutputStream 一起使用。我有两个 ivars NSInputStream *_inputStream 和 NSOutputStream *_outputStream。

下面给了我两条错误信息:

CFStreamCreatePairWithSocketToHost(NULL,
  (__bridge_retained CFStringRef)self.hostname, self.port,
  (CFReadStreamRef *)&_inputStream, (CFWriteStreamRef *)&_outputStream);

error: cast of an indirect pointer to an Objective-C pointer to 'CFReadStreamRef *' (aka 'struct __CFReadStream **') is disallowed with ARC
error: cast of an indirect pointer to an Objective-C pointer to 'CFWriteStreamRef *' (aka 'struct __CFWriteStream **') is disallowed with ARC

我该如何解决这个问题？我尝试使用 __bridge 但我收到了类似的错误消息。

Answer 1

传递指向实际 CFReadStreamRef 和 CFWriteStreamRef 变量的指针，然后在分配给您的 NSType 时进行转换。基本上:

CFThingRef cfThing = NULL;
CFFunctionGetThing(&cfThing);
NSThing * nsThing = cfThing;

当然，您必须添加适当的桥接转换并为 cfThing 执行所有适当的引用计数操作。