工程中含有以下命名空间:

1. System.Net.Security:
   sslStream.AuthenticateAsServer
   sslStream.AuthenticateAsClient
2. System.Xml:
   XmlDocument
3. System.Net.WebSockets
   ClientWebSocket.ConnectAsync
4. System.Net:
   FtpWebRequest
   HttpWebRequest.GetResponse
   代码中含有这些命名空间，导出的xcode工程会含有dlopen

同时link.xml含有一下内容

1. <namespace fullname="System.ComponentModel" preserve="all"/>
2. <type fullname="System.Net.IWebProxy" preserve="all" />
3. <type fullname="System.Net.WebRequest" preserve="all" />

也会含有dlopen