CFNetwork SSLHandshake使用套接字流失败（-9806）

Question

我的域名有TLS证书，可以在浏览器中使用https。我试图理解这些证书是如何工作的，但它没有意义。有人能指出我如何使用套接字流设置TLS的正确方向吗？从Apple的文档来看，它听起来像你需要做的只是[stream setProperty:NSStreamSocketSecurityLevelNegotiatedSSL forKey:NSStreamSocketSecurityLevelKey];，如果服务器证书有效，那么一切都很好。我想我错过了什么。

CFReadStreamRef readStream;
CFWriteStreamRef writeStream;

CFStreamCreatePairWithSocketToHost(NULL, (__bridge CFStringRef)[url host], port, &readStream, &writeStream);

_inputStream = (__bridge_transfer NSInputStream *)readStream;
_outputStream = (__bridge_transfer NSOutputStream *)writeStream;

[_inputStream setProperty:NSStreamSocketSecurityLevelNegotiatedSSL forKey:NSStreamSocketSecurityLevelKey];
[_outputStream setProperty:NSStreamSocketSecurityLevelNegotiatedSSL forKey:NSStreamSocketSecurityLevelKey];

[_inputStream scheduleInRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];
[_outputStream scheduleInRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];

[_inputStream setDelegate:self];
[_outputStream setDelegate:self];

[_inputStream open];
[_outputStream open];