Argument aggregator for avoid nesting withUnsafeBytes

WithUnsafeBytesArgsAggregator.swift

private func argAgregate<ResultType> (
    dataObjects: [Data],
    callback: (([UnsafeRawBufferPointer]) -> ResultType)
) -> ResultType {
    var callbacks = [(([UnsafeRawBufferPointer]) -> Void)]()
    let withOutFirstDataObjects = dataObjects.dropFirst()
    withOutFirstDataObjects.enumerated().forEach { (index, value) in
        callbacks.append { pointers in
            dataObjects[index + 1].withUnsafeBytes { pointer in
                var newPointers: [UnsafeRawBufferPointer] = []
                newPointers.append(contentsOf: pointers)
                newPointers.append(pointer)
                callbacks[index + 1](newPointers)
            }            }
    }
    dataObjects[0].withUnsafeBytes { firstPointer in
        callbacks[0]([firstPointer])
    }
}


// to use it

argAgregate(dataObjects: [key, vi, dataIn]) { pointers in
    // no array destructuring in swift, lame
    let keyPointer =  pointers[0]
    let viPointer = pointers[1]
    let dataInPointer = pointers[2]
    CCCrypt(
       CCOperation(op),
       CCAlgorithm(alg),
       CCOptions(kCCOptionPKCS7Padding),
       keyPointer.bindMemory(to: UInt8.self).baseAddress,
       key.count,
       viPointer.bindMemory(to: UInt8.self).baseAddress,
       dataInPointer.bindMemory(to: UInt8.self).baseAddress,
       dataIn.count,
       dataOutPointer.bindMemory(to: UInt8.self).baseAddress,
       dataOut.count,
       &dataOutMoved
   )

}