Use Melos to install the dependencies of the flutter_zxing project. Melos is a tool that helps you manage multiple Dart packages in a single repository. To install Melos, use the following command:
```bash
pub global activate melos
```
To install the dependencies of the flutter_zxing project, use the following command:
```bash
melos bootstrap
```
To allow the building on iOS and MacOS, you need to run the following command:
```bash
cd scripts
sh update_ios_macos_src.sh
```
Now you can run the flutter_zxing example app on your device or emulator.