How can I download and install macOS 10.12 SDK? I need to download the macOS 10.12 SDK to build and run ispwDownloader (because there were no built downloads).

How can I download and install the SDK? Searching the Web has not been helpful with the solution.
@Nimesh Neema, the SDKs are stored in /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/, and I got the 10.12 SDK from here.

It works.