MacOSX/Framework/VLCMedia.m: Don't forget to init the metaDictionary, when initing from a media_descriptor object.

extras/MacOSX/Framework/Sources/VLCMedia.m

@@ -280,6 +280,7 @@ static void HandleMediaDurationChanged(const libvlc_event_t *event, void *self)
         libvlc_media_descriptor_retain( md );
         p_md = md;
         
+        metaDictionary = [[NSMutableDictionary alloc] initWithCapacity:3];
         [self initInternalMediaDescriptor];
     }
     return self;
@@ -385,6 +386,7 @@ static void HandleMediaDurationChanged(const libvlc_event_t *event, void *self)
                                        withObject:newValue];
             return;
         }
+
         @synchronized(metaDictionary) {
             [metaDictionary setValue:newValue forKeyPath:metaType];
         }