I want to use Google App Indexing with my web pages and iOS app. I do support Universal Links (or deep links in Google lingo) with Apples Search and have my web pages set up accordingly.
From Googles documentation I am unable to find out if I really need to add the Google App Indexing SDK. The SDK does not give me any required functionality and I would prefer to skip it - but does Google rely on the SDK to be able to do the magic?
I am not doing any indexing of in app content, the only thing I want to be indexed is the web pages, and get the according deep links.
To enable App Indexing in your iOS App, adding the Google App Indexing SDK is mandatory as the documentation suggests. This way it will be possible for your App content to be searchable by users conducting Google queries, producing results that will lead the users to open or install your App.
Concerning the SDK, it will influence ranking, whether or not the user has your App installed. This means that if your App is indexed, Google will use the content within your App as a signal in ranking and not just your web content. Users will also see an enhanced UI with your App icon on the search results page.
Hope this helps.
You are right, getting Google search results to deep-link into your app is achievable using only Universal Links and having your web content naturally feature in Google search results.
The Google documentation isn't great, but there are two major reasons you'd want to integrate the Google App Indexing SDK:
The first, as the documentation does say, is so that Google ranks your 'app content' higher in Google search results than if you didn't integrate the SDK. My guess is that 'app content' here is defined as your web content with app related meta data, such as the <link rel=alternate> tag specified in the documentation. I've yet to find any way to validate/verify to what degree this helps - we have to trust the documentation for now.
The second is that currently, your deep-linking will only work from Safari Mobile. To facilitate deep-linking from Google search results into your app in Chrome for iOS will require implementation of Google's SDK, which will also provision a "back to Google" button in your app. To see whether this is worth doing you'd have to check your analytics to see how many of your iOS users are using Chrome instead of Safari Mobile as their main browser on iPhone.
Source for second reason: https://www.youtube.com/watch?v=6NFRNamQGCc&feature=youtu.be&t=268
来源：https://stackoverflow.com/questions/33496961/is-google-app-indexing-sdk-required-in-ios-for-google-deeplinking