takePicture = async function() {
if (this.camera) {
  const options = { quality: 0.5, base64: true };
  const data = await this.camera.takePictureAsync(options);
  console.log(data.uri);
  console.log(data);

  var promise = CameraRoll.saveToCameraRoll(data.uri);
  promise.then(function(result) {
    console.log('save succeeded ' + result);
  }).catch(function(error) {
    console.log('save failed ' + error);
  });
}