This framework provides a Swift implementation of 'ByteBuffer' which provides various tools for reading binary data. This includes support for bit fields.

ByteBuffer is a struct and reading/writing data mutates the internal state so it needs to be a var.

var buffer = ByteBuffer(data: data)

let bitField = try buffer.readBool(bits: 1)
let field2 = try buffer.readByte(bits: 3)
let field3 = try buffer.readByte(bits: 4)
let field4 = try buffer.readUInt64()

Calling rewind() resets the read position and allows you to start reading from the beginning of the buffer.

Data can be written as whole bytes or other data types written into bit increments. The resulting Data can be read out and easily converted to hex.

var buffer = ByteBuffer()
buffer.write(bytes: [0x01, 0x02, 0x03, 0x04])
buffer.write(short: 312, bits: 9)
buffer.write(byte: 128, bits: 7)
buffer.data.hexEncodedString()

There are some extensions on Data to make working with hex data easier. See Data(hexEncoded:) and Data.hexEncodedString.