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How does one go about creating a smart folder on the filesystem programmatically from a Cocoa app? It doesn’t appear that NSFileManager got any new methods in Tiger that will support this functionality.


A smart folder is actually just an XML file, which you can see by opening it with a text editor. The format looks to be fairly obvious; I would assume if you generate a properly-structured file with the right extension then it will work as expected.

Just out of curiosity (I’m still using Panther), can you post the XML from an example file/folder? –JediKnil


Perhaps you should look in the Spotlight API, instead of cocoa?


Here’s a saved search that searches for items with the name “foo” in the home folder:

<!DOCTYPE plist PUBLIC “-//Apple Computer//DTD PLIST 1.0//EN” “http://www.apple.com/DTDs/PropertyList-1.0.dtd”>

CompatibleVersion 0 RawQuery (* = "foo*"wcd || kMDItemTextContent = "foo*"cd) && (kMDItemContentType != com.apple.mail.emlx) && (kMDItemContentType != public.vcard) SearchCriteria AnyAttributeContains foo CurrentFolderPath /Users/mikeash FXCriteriaSlices FXSliceKind Skin Value KI** FXSliceKind Slsv Value DA** FXScope 1396926573 FXScopeArrayOfPaths kMDQueryScopeHome Version 10.4 ViewOptions SidebarWidth 183 ToolbarVisible ViewStyle qrsb WindowBounds bottom 0 left 0 right 0 top 0

From some tinkering, it seems that the Finder executes the RawQuery in the folders inside SearchCriteria/FXScopeArrayOfPaths. All other values are either aestetic or used by the query generation UI (in particular FXCriteriaSlices/* seem to be ignored when executing the query, but are used to fill in the UI and regenerate the query when the user manipulates the search criteria).


The default constraint within the predicate query string generated by Finder is curious… It excludes the Mail and vcard UTI types.

i.e.,:

&& (kMDItemContentType != com.apple.mail.emlx) && (kMDItemContentType != public.vcard)

To create more interesting Smart Folders (think BeFS style…), try this for a folder of persons in your Address Book:

The differences between Finder Smart Folders and Spotlight query result windows seem arbitrary and are likely artifical. For instance, Finder is not the owning process of the Spotlight query result window lives, SystemUIServer is. The question Apple UE must be considering for future releases is whether the technology basis behind Smart Folders, the metadata store, indexing system and attributes and APIs, will be grokked by enough of the user base to move Smartness outside of applications and into something that is not the Finder or a Spotlight query result window. I see Smartness as enabling the owner and user of any computational resource to be able to choose the manner and method best suited to the nature of the data, be it based on the the goal at hand or on the users own conceptual view of their environment. Once one begins to think about checking their mail as not the act of opening Mail.app and looking in the Inbox but instead clicking a single Smart Folder in Finder to present new, interesting and unread mail… one can begin to see the future taking shape.

.dpm


It’s easy enough to use the results from SmartFolders in your code. The trick is to realise that they are created by the Finder which is written in Carbon rather than Cocoa, and thus the query string format is for a MDQueryCreate rather than a NSPredicate. I assume that eventually someone might write some code to allow the transforming of the query strings…

It also seems the Cocoa implementation for metadata queries is incomplete. I mean that the NSMetadataQuery NSMetadataQueryDidUpdateNotification seem to be missing the array of changed items - could be a bug.

If you’re not afraid of a little Carbon (is this allowed on this site?) then you can use the following to build a smart folder query:

NSString * filePath = @”/Users/me/xxyz.savedSearch”; //i.e. a SmartFolder NSDictionary doc = [NSDictionary dictionaryWithContentsOfFile:filePath]; NSString * raw = [doc objectForKey:@”RawQuery”]; // Ugh, Carbon from now on… MDQueryRef query = MDQueryCreate(kCFAllocatorDefault, (CFStringRef)rawQuery, NULL, NULL); CFNotificationCenterRef nc = CFNotificationCenterGetLocalCenter(); CFNotificationCenterAddObserver(nc, (void)self, &MyCallBack, NULL/name/, query, CFNotificationSuspensionBehaviorDeliverImmediately); MDQueryExecute(query, kMDQueryWantsUpdates);

// elsewhere add the callback static void MyCallBack(CFNotificationCenterRef center, void *observer, CFStringRef name, const void *object, CFDictionaryRef userInfo) { if(name==kMDQueryDidFinishNotification) { // Finished gathering the query results } else if(name==kMDQueryDidUpdateNotification) { // In userInfo look for arrays of MDItem keyed on: // kMDQueryUpdateAddedItems // kMDQueryUpdateRemovedItems // kMDQueryUpdateRemovedItems …