MASTG-KNOW-0073: iOS Network APIs

Since iOS 12.0 the Network framework and the URLSession class provide methods to load network and URL requests asynchronously and synchronously. Older iOS versions can utilize the Sockets API.

Network Framework

The Network framework was introduced at The Apple Worldwide Developers Conference (WWDC) in 2018 and is a replacement to the Sockets API. This low-level networking framework provides classes to send and receive data with built in dynamic networking, security and performance support.

TLS 1.3 is enabled by default in the Network framework, if the argument using: .tls is used. It is the preferred option over the legacy Secure Transport framework.

URLSession

URLSession was built upon the Network framework and utilizes the same transport services. The class also uses TLS 1.3 by default, if the endpoint is HTTPS.

URLSession should be used for HTTP and HTTPS connections, instead of utilizing the Network framework directly. The URLSession class natively supports both URL schemes and is optimized for such connections. It requires less boilerplate code, reducing the possibility for errors and ensuring secure connections by default. The Network framework should only be used when there are low-level and/or advanced networking requirements.

The official Apple documentation includes examples of using the Network framework to implement netcat and URLSession to fetch website data into memory.