Determines how much space (in bytes) is available to save a photo to the camera roll.
camera_error_t camera_roll_available_photo(camera_handle_t handle, long long *size)
The handle returned by a call to the camera_open() function.
A pointer that is updated with the number of bytes available for saving the photo.
The size argument is updated with the amount of space in bytes.
CAMERA_OK when the function successfully completes, otherwise another camera_error_t value that provides the reason that the call failed.