iOS 8 How-To: Use Siri to search the App Store, iTunes Store and iBooks Store
Sometimes searching the App Store can be an overwhelming task. You might already know what you want to download, or other times you might get distracted when you open the store and forget why you were there, and typing in what you want to download is old fashioned now. With iOS 8, you can use Siri to search the App Store, iTunes Store, iBooks Store, and more for you. It’s all a matter of asking Siri with the right commands.
Press down and hold on the home button for two seconds for Siri to appear.
For example you can say something like, “Search the App Store for sports apps,” and Siri will open up the App Store and bring you to the search results of sports.