Google will be indexing apps for iPhone and iPad, which will let users open specific app content from a Google search.
In both the Google Search and Chrome apps for iPhone and iPad, users will have the ability to open another app based on the search they have performed. For instance, if you do a search for making a reservation at a specific restaurant, your results may give you the option to make the reservation on that restaurant's page in the OpenTable app.
Indexed content will begin appearing in search results over the next few weeks, according to Google:
Starting today, we're bringing App Indexing to iOS apps as well. This means users on both Android and iOS will be able to open mobile app content straight from Google Search. Indexed links from an initial group of apps we've been working with will begin appearing on iOS in search results both in the Google App and Chrome for signed-in users globally in the coming weeks.
Google began doing this same thing on Android last month. Apps that need to support indexing will also need to support deep linking, and enable other features in order to work with Google's indexing.
As stated above, this feature will roll out over a period of weeks. In the meantime you can download both the Google Search and Chrome apps from the App Store.