How do I debug a Swift dependency tree analysis?

Hi, love the gem, works like magic with a brand new Swift project but when I run the script for an existing production codebase I get the following output in `origin.js`

```
var dependencies = {"links":[],"links_count":0,"objects":{}}
```

Seems like nothing gets parsed and I wonder why and how would debug this?

Also is there a way to run it for an arbitrary folder with Swift code?