Back Button on Mobile Application

I am having a hard time figuring out the best practices on Back Button functionality within a mobile application because I have seen a lot of conflicting viewpoints.

I have taken to the developer guides for iOS and Android to figure this out and have found that both recommend using the back arrow in the mobile application to navigate up the hierarchy of your application as opposed to using it like a browser back button which navigates chronologically.

In either developer guide, I have not found specific guidance for how to handle navigating back to a search results page. For example, in my application we are implementing a global search which can be used to find and navigate to any object in the application. But I don't know whether the back button should go back to the search results or not once they have navigated by clicking one of the objects in the search results. And if not, then how I should allow the user to be able to view their last search.

And to make it more confusing, I have taken a look at the functionality of what I consider to be similar apps hierarchically to mine: Google Drive and GMail. Both of these apps break the hierarchical back button navigation when search is involved. For example, when I search for a folder this is the sequence: Home -> Search: Assembly -> Folder: Assembly -(back button)> Search:Assembly -(back button)> Home.

Please advise, since most of the other questions about this provide outdated or inconsistent viewpoints.

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