又如LZ关心ios的网络部分,那么看
https://developer.apple.com/library/ios/#documentation/NetworkingInternetWeb/Conceptual/NetworkingOverview/Introduction/Introduction.html#//apple_ref/doc/uid/TP40010220
这里面提供了方向
OS X and iOS Provide APIs at Many Levels
You can accomplish the following networking tasks in both OS X and iOS with identical or nearly identical code:
Perform HTTP/HTTPS requests, such as GET and POST requests
Establish a connection to a remote host, with or without encryption or authentication
Listen for incoming connections
Send and receive data with connectionless protocols
Publish, browse, and resolve network services with Bonjour