Fix attempt for #17

Author: stefanceriu

SCXcodeMinimap/SCMiniMapView.h

@@ -15,7 +15,7 @@
 @property (nonatomic, strong) SCSelectionView *selectionView;
 
 @property (nonatomic, weak) NSScrollView *editorScrollView;
-@property (nonatomic, assign) NSTextView *editorTextView;
+@property (nonatomic, strong) NSTextView *editorTextView;
 
 - (void)updateTextView;
 - (void)updateSelectionView;

SCXcodeMinimap/SCXcodeMinimap.m

@@ -151,7 +151,7 @@ - (void)onDidFinishSetup:(NSNotification*)sender
 
     /* Setup Associated Objects */
     objc_setAssociatedObject(editorScrollView,  &kKeyMiniMapView, miniMapView, OBJC_ASSOCIATION_ASSIGN);
-    objc_setAssociatedObject(editorDocument,    &kKeyMiniMapView, miniMapView, OBJC_ASSOCIATION_ASSIGN);
+    objc_setAssociatedObject(editorDocument,    &kKeyMiniMapView, miniMapView, OBJC_ASSOCIATION_RETAIN);
 
     if ([[NSUserDefaults standardUserDefaults] boolForKey:SCXodeMinimapIsInitiallyHidden]) {
         [miniMapView hide];