Ever wanted to preview files like Apple's Mail app does? Quick Look is an Apple framework that lets you do just that.

1. Quick Look for iOS
By Robert Brown
@robby_brown

2. What is Quick Look?
Previews all common files
Includes AirPrint
Available since iOS 4.0

3. QLPreviewItem
Protocol for previewing files
(Required) -(NSURL)previewItemURL
Must be a file URL (i.e. file://somefile.txt)
Use [NSURL fileURLWithPath:somePath]
(Optional) -(NSString)previewItemTitle
NSURL conforms to QLPreviewItem

4. QLPreviewController
Subclass of UIViewController
Can be pushed into view or presented modally
Must have a data source
May have a delegate

5. QLPreviewController
iWork Documents Text files (with supported
UTI)
Microsoft Office
Documents (1997+) CSV
RTF HTML
PDF
Images

6. QLPreviewControllerDataSource
Similar to UITableViewDataSource
Tells how many QLPreviewItems it provides
Returns a QLPreviewItem when asked

7. QLPreviewControllerDelegate
Provides call backs for when the view will dismiss and
did dismiss
Provides a couple animation call backs
One call back asking permission to open URLs

8. UIDocumentInteractionController
Manages user interactions with files on the local system
More control than QLPreviewController
Only previews one file
Provides easy access to a file’s icons
Provides access to annotation property for passing
custom data with a file

9. Inter-app File Sharing
Files aren’t “shared,” they are copied into the app’s
sandbox (~Documents/Inbox)
An app’s Info.plist specifies which files are accepted
with the CFBundleDocumentTypes key
CFBundleDocumentTypes is an array of dictionaries

10. Inter-app File Sharing
CFBundleDocumentTypes sub keys:
CFBundleTypeName: Name of the type
CFBundleTypeIconFiles: array of icons (smallest to
largest)
LSItemContentTypes: array of UTIs
LSHandlerRank: Owner, Alternate, None, Default

11. Inter-app File Sharing
LSHandlerRank (in order of precedence):
Owner: Creator of these files
Alternate: Secondary viewer
None: Files can only be loaded through iTunes
Default: Accepts files

12. Inter-app File Sharing
Developer tip: Use mdls command on a file to see its
UTI tree

13. Questions?

14. Demo

15. Want to learn more?
robsprogramknowledge.blogspot.com
Document Interaction Programming Topics for iOS
WWDC 2010 Session 106