Compression of an image on an iPhone like on whatsapp

I'm trying to find an image compression algorithm in the Swift programming language, as in the WhatsApp messenger. In the programming language Java under OS Android I found quickly, and under the platform iOS have difficulties.

Here is the image compression algorithm for Android:

public static File saveBitmapToFile(File file){
    try {
        // BitmapFactory options to downsize the image
        BitmapFactory.Options o = new BitmapFactory.Options();
        o.inJustDecodeBounds = true;
        o.inSampleSize = 6;
        // factor of downsizing the image

        FileInputStream inputStream = new FileInputStream(file);
        //Bitmap selectedBitmap = null;
        BitmapFactory.decodeStream(inputStream, null, o);
        inputStream.close();

        // The new size we want to scale to
        final int REQUIRED_SIZE=75;

        // Find the correct scale value. It should be the power of 2.
        int scale = 1;
        while(o.outWidth / scale / 2 >= REQUIRED_SIZE &&
                o.outHeight / scale / 2 >= REQUIRED_SIZE) {
            scale *= 2;
        }

        BitmapFactory.Options o2 = new BitmapFactory.Options();
        o2.inSampleSize = scale;
        inputStream = new FileInputStream(file);

        Bitmap selectedBitmap = BitmapFactory.decodeStream(inputStream, null, o2);
        inputStream.close();

        // here i override the original image file
        file.createNewFile();
        FileOutputStream outputStream = new FileOutputStream(file);

        selectedBitmap.compress(Bitmap.CompressFormat.JPEG, 70 , outputStream);

        return file;
    } catch (Exception e) {
        return null;
    }
}

This algorithm compresses the image to 100 KB. If you can tell me how to duplicate this code into the Swift programming language, I'll be very grateful.

I have studied many articles, tried to use different algorithms (unfortunately I can not publish them, because I do not remember the sites), but I did not find the necessary solution.