How to transfer images via Bluetooth (LE) to a desktop application

We are currently trying to implement the transmission of images from a mobile device (in this case an IPhone) to a desktop application. We tried already the Bluetooth Serial plugin which works fine for Android but does not list any devices when scanning for our desktop application.

To cover iOS support (AFAIK iOS only supports BluetoothLE), we reimplemented our desktop application to use BluetoothLE and behave like a peripheral. Also we altered our Ionic application to use BLE plugin.

Now BluetoothLE only supports the transmission of packages with the size of 20 Byte whilst our image is about 500kb big. Now we could obviously split our image to chunks and transmit it with the following function (taken from this gist):

function writeLargeData(buffer) {
    console.log('writeLargeData', buffer.byteLength, 'bytes in',MAX_DATA_SEND_SIZE, 'byte chunks.');
    var chunkCount = Math.ceil(buffer.byteLength / MAX_DATA_SEND_SIZE);
    var chunkTotal = chunkCount;
    var index = 0;
    var startTime = new Date();

    var transferComplete = function () {
        console.log("Transfer Complete");
    }

    var sendChunk = function () {
        if (!chunkCount) {
            transferComplete();
            return; // so we don't send an empty buffer
        }

        console.log('Sending data chunk', chunkCount + '.');

        var chunk = buffer.slice(index, index + MAX_DATA_SEND_SIZE);
        index += MAX_DATA_SEND_SIZE;
        chunkCount--;

        ble.write(
            device_id, 
            service_uuid, 
            characteristic_uuid, 
            chunk, 
            sendChunk,         // success callback - call sendChunk() (recursive)
            function(reason) { // error callback
                console.log('Write failed ' + reason);
            }
        )
    }
    // send the first chunk
    sendChunk();
}

Still this would mean for us that we would have to launch about 25k transmissions which I assume will take a long time to complete. No I wonder why is that the image transmission via Bluetooth is that handicapped.

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