Default

Handle URL open from other apps in iOS

For short, declare UTImportedTypeDeclarations(for types that are not predefined as System Uniform Type Identifiers), CFBundleDocumentTypes in Info.plist, UIApplicationLaunchOptionsURLKey in

[launchOptions valueForKey:UIApplicationLaunchOptionsURLKey]

And for multitask apps, additionally respond to

(BOOL)application:(UIApplication *)application openURL:(NSURL *)url sourceApplication:(NSString *)sourceApplication annotation:(id)annotation // for iOS 4.2+

or

(BOOL)application:(UIApplication *)application handleOpenURL:(NSURL *)url // for iOS 2.0+, deprecated.

One little trick to handle ALL file types:

<key>CFBundleDocumentTypes</key>
<array>
    <dict>
        <key>CFBundleTypeName</key>
        <string>All Files</string>
        <key>LSItemContentTypes</key>
        <array>
            <string>public.data</string>
            <string>public.content</string>
        </array>
    </dict>
</array>