You can see iCloud Drive files right on your iPhone, iPod touch, or iPad. Here's how!
Ever since Apple released iOS 9, we've had the iCloud Drive app, which lets you see everything and anything stored in your iCloud Drive on iPhone, iPod touch, iPad, and even Mac. (It basically turns the DocumentPicker interface into its own app.) In iOS 9, the iCloud Drive app starts off hidden by default. You can still turn it back on at any time in Settings.
Note: In iOS 10, you no longer have the option to turn the iCloud Drive app on or off. If you don't have it on your device, you can get it from the App Store.
How to turn on the iCloud Drive app in iOS 9
Launch the Settings app from your Home screen.
Tap on iCloud.
Tap on iCloud Drive.
Switch Show on Home Screen to On.
Click the Home button to exit Settings.
Launch the iCloud Drive app from your Home screen. (If you have trouble finding it, swipe down to bring up Spotlight Search and start typing "iCloud" until it appears.)
If you ever decide you want to hide it again, you can repeat the same process and switch it to Off.
Note: On iOS 10, if you want to hide the iCloud Drive app, you can remove it from your Home screen the same way you would delete an app.