gr-iio software package provides IIO blocks for GnuRadio, you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install gr-iio
gr-iio is installed in your system.
Make ensure the gr-iio package were installed using the commands given below,
$ sudo dpkg-query -l | grep gr-iio *
You will get with gr-iio package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Library development |
| Package | gr-iio |
| Version | 0.1.67-1 |
| Description | IIO blocks for GnuRadio |
| Sub Section | libdevel |