grpc-swift/docs/apple-platforms.md

Apple Platforms

NIO offers extensions to provide first-class support for Apple platforms (iOS 12+, macOS 10.14+, tvOS 12+, watchOS 6+) via NIO Transport Services. NIO Transport Services uses Network.framework and DispatchQueues to schedule tasks.

To use NIO Transport Services in gRPC Swift you need to provide a NIOTSEventLoopGroup to the configuration of your server or client connection. gRPC Swift provides a helper method to provide the correct EventLoopGroup based on the network preference:

PlatformSupport.makeEventLoopGroup(loopCount:networkPreference:) -> EventLoopGroup

Here networkPreference defaults to .best, which chooses the .networkFramework implementation if it is available (iOS 12+, macOS 10.14+, tvOS 12+, watchOS 6+) and uses .posix otherwise.

Using the TLS provided by Network.framework via NIO Transport Services is not currently supported. Instead, TLS is provided by NIOSSL.