If you are developer and using Mac, you must absolutely know offline documentation and snippets browser Dash by now. If not, go check it out. It will change your life.
This morning I submitted my own docset for NativeScript 1.7.1. It's been accepted later today and can be found in
Preferences -> Downloads -> User Contributed. Search for "NativeScript".
I'm planning on adding How-to's and guides from the official documentation site in it in the upcoming release.