I am doing both android and iOS development. I've been struggling to find out the best practices and most updated trend on iOS development architecture in swift in the shape of sample project like the way Google android has on GitHub.
and no luck with Apple GitHub :(
Any suggestion ?
This question is outside the scope of this forum, since it's about Apple-specific development. I'm assuming you are a paying Apple developer, and/or you have an Apple developer account ( you will need one if you want to code-sign and release/distribute your application, even within an enterprise environment). If so, you should look around the Apple developer support site (developer.apple.com). WWDC videos, sample code, development guides, SDK references, the Apple Developer forums, etc., are available that should probably give you a pretty good idea about how to go about developing a "best-practice" iOS application. Also, the Human Interface Guidelines describe what Apple thinks a well-behaved iOS application should look like.
You should be aware that some best practices are somewhat of a moving target as Apple decides to evolve the visual look and feel of its interfaces as new releases of the operating system are introduced. However, basic architectural principles of how applications are put together have evolved more slowly, and are pretty much the same across iOS, iPadOS, macOS, watchOS, and tvOS.