Programming iOS 6, 3rd Edition

Document Types

Your app can declare itself willing to open documents of a certain type. In this way, if another app obtains a document of this type, it can propose to hand the document off to your app. For example, the user might download the document with Mobile Safari, or receive it in a mail message with the Mail app; now we need a way to get it from Safari or Mail to you.

To let the system know that your app is a candidate for opening a certain kind of document, you will configure the “Document types” (CFBundleDocumentTypes) key in your Info.plist. This is an array, where each entry will be a dictionary specifying a document type by using keys such as “Document Content Type UTIs” (LSItemContentTypes), “Document Type Name” (CFBundleTypeName), CFBundleTypeIconFiles, and LSHandlerRank. Far and away the simplest method for configuring the Info.plist is through the interface available in the Info tab when you edit the target.

For example, suppose I want to declare that my app opens PDFs. My Info.plist could contain this simple entry (as seen in the standard editor):

Document types                       (1 item)
    Item 0                           (1 item)
        Document Type Name           PDF
        Document Content Type UTIs   (1 item)
            Item 0                   com.adobe.pdf

Now suppose the user receives a PDF in an email message. The Mail app can display this PDF, but the user can also tap the Action button to bring up an activity view offering, among other things, to open the file in my app. (The interface will resemble Figure 36-2, with my app listed as one of the buttons.) ...