Bitwise shift multiple bytes in Data

Why? Swift doesn't have a built-in way of shifting the bits from multiple bytes inside Data.

The below extension on Data allows you to do exactly that:

var exampleData = Data([40, 127, 67]) // ["00101000", "01111111", "01000011"]
// Left shift:
exampleData << 10                     // ["11111101", "00001100", "00000000"]
// Left shift and set:
exampleData <<= 10                    // ["11111101", "00001100", "00000000"]

exampleData = Data([40, 127, 67])     // ["00101000", "01111111", "01000011"]
// Right shift:
exampleData >>> 10                    // ["00000000", "00001010", "00011111"]
// Right shift and set
exampleData >>>= 10                   // ["00000000", "00001010", "00011111"]

Note:

• For left shift use either << or <<=.
• For right shift use either >>> or >>>=. Right shifts are always logical right shifts, arithmetic right shifts are not supported.
• The above operators don't overwrite the built-in Swift bitwise operators like << or <<=. They are only used if the left side of the expression is of type Data.

Testing:

You can use following function to print the values of Data as binary for testing.

func printData(_ data: Data) {
    let result: [String] = data.map { byte in
        var byteString = String(byte, radix: 2)
        (0..<(8-byteString.count)).forEach { _ in byteString = "0"+byteString }
        return byteString
    }
    print(result)
}

printData(exampleData)