Refactor search to make a little more sense w/ main thread limitation

Submariner/SBSearchResult.swift

@@ -9,14 +9,21 @@
 import Cocoa
 
 @objc class SBSearchResult: NSObject {
+    /// Used for bindings and contains the actual tracks fetched from `fetchTracks:`.
     @objc var tracks: [SBTrack] = []
     @objc let query: String // NSString
 
-    // FIXME: Nasty hack for SBServerSearchController since the tracks were sourced from a different thread
-    // it should be an array of IDs and the UI thread fetches that
-    @objc func replaceManagedInstancesForThread(managedObjectContext: NSManagedObjectContext) {
-        tracks = tracks.map { track in
-            managedObjectContext.object(with: track.objectID) as! SBTrack
+    /// Contains the list of tracks to fetch on the main thread, and fills `tracks` from that.
+    ///
+    /// This can be appended to.
+    var tracksToFetch: [NSManagedObjectID] = []
+
+    /// Updates the tracks array after getting the results.
+    ///
+    /// This has to be done on the main thread, as the parse operation that builds the list runs off the main thread.
+    @objc func fetchTracks(managedObjectContext: NSManagedObjectContext) {
+        tracks = tracksToFetch.map { trackID in
+            managedObjectContext.object(with: trackID) as! SBTrack
         }
     }
 

Submariner/SBServerSearchController.m

@@ -91,7 +91,7 @@ - (void)subsonicSearchResultUpdatedNotification:(NSNotification *)notification {
         SBSearchResult *results = [notification object];
         // HACK: We can't use the objects that were fetched on another thread.
         // Refetch on this one from ours. Better way possible?
-        [results replaceManagedInstancesForThreadWithManagedObjectContext: self.managedObjectContext];
+        [results fetchTracksWithManagedObjectContext: self.managedObjectContext];
         [self setSearchResult:[notification object]];
     });
 }

Submariner/SBSubsonicParsingOperation.swift

@@ -477,12 +477,12 @@ class SBSubsonicParsingOperation: SBOperation, XMLParserDelegate {
                 // the song element has the same format as the one used in nowPlaying, complete with artist name without ID
                 updateTrackDependenciesForDirectoryIndex(track, attributeDict: attributeDict)
                 // objc version did some check in playlist, which didn't make sense
-                currentSearch.tracks.append(track)
+                currentSearch.tracksToFetch.append(track.objectID)
             } else {
                 logger.info("Creating track ID \(id, privacy: .public) for search")
                 let track = createTrack(attributes: attributeDict)
                 updateTrackDependenciesForDirectoryIndex(track, attributeDict: attributeDict)
-                currentSearch.tracks.append(track)
+                currentSearch.tracksToFetch.append(track.objectID)
             }
         } else {
             logger.warning("Current search was null on a song element")