TunnelKit is a simplified OpenVPN® and WireGuard® client library for the iOS and macOS platforms. It’s a hard fork of PIATunnel, a library that I developed and maintained while working at Private Internet Access, a VPN provider.
Supports AES-CBC and AES-GCM ciphers, a couple of SHA digests and TLS verification. The feature set is smaller than the standard OpenVPN clients, yet the library provides a much easier, not to mention native Swift API.