macosx: contacting an app using SBApplication can fail, be a bit more...

macosx: contacting an app using SBApplication can fail, be a bit more conservative to prevent runtime exceptions

modules/gui/macosx/intf.m

@@ -1394,7 +1394,7 @@ static bool f_appExit = false;
             iTunesApplication *iTunesApp = (iTunesApplication *) [SBApplication applicationWithBundleIdentifier:@"com.apple.iTunes"];
             if (iTunesApp && [iTunesApp isRunning]) {
                 if ([iTunesApp playerState] == iTunesEPlSPaused) {
-                    msg_Dbg(p_intf, "Unpause iTunes...");
+                    msg_Dbg(p_intf, "unpausing iTunes");
                     [iTunesApp playpause];
                 }
             }
@@ -1402,12 +1402,16 @@ static bool f_appExit = false;
 
         if (b_has_spotify_paused) {
             SpotifyApplication *spotifyApp = (SpotifyApplication *) [SBApplication applicationWithBundleIdentifier:@"com.spotify.client"];
+            if (spotifyApp) {
+                if ([spotifyApp respondsToSelector:@selector(isRunning)] && [spotifyApp respondsToSelector:@selector(playerState)]) {
                     if ([spotifyApp isRunning] && [spotifyApp playerState] == kSpotifyPlayerStatePaused) {
-                msg_Dbg(p_intf, "Unpause Spotify...");
+                        msg_Dbg(p_intf, "unpausing Spotify");
                         [spotifyApp play];
                     }
                 }
             }
+        }
+    }
 
     b_has_itunes_paused = NO;
     b_has_spotify_paused = NO;
@@ -1437,7 +1441,7 @@ static bool f_appExit = false;
                 iTunesApplication *iTunesApp = (iTunesApplication *) [SBApplication applicationWithBundleIdentifier:@"com.apple.iTunes"];
                 if (iTunesApp && [iTunesApp isRunning]) {
                     if ([iTunesApp playerState] == iTunesEPlSPlaying) {
-                        msg_Dbg(p_intf, "Pause iTunes...");
+                        msg_Dbg(p_intf, "pausing iTunes");
                         [iTunesApp pause];
                         b_has_itunes_paused = YES;
                     }
@@ -1447,13 +1451,18 @@ static bool f_appExit = false;
             // pause Spotify
             if (!b_has_spotify_paused) {
                 SpotifyApplication *spotifyApp = (SpotifyApplication *) [SBApplication applicationWithBundleIdentifier:@"com.spotify.client"];
+
+                if (spotifyApp) {
+                    if ([spotifyApp respondsToSelector:@selector(isRunning)] && [spotifyApp respondsToSelector:@selector(playerState)]) {
                         if ([spotifyApp isRunning] && [spotifyApp playerState] == kSpotifyPlayerStatePlaying) {
-                    msg_Dbg(p_intf, "Pause Spotify...");
+                            msg_Dbg(p_intf, "pausing Spotify");
                             [spotifyApp pause];
                             b_has_spotify_paused = YES;
                         }
                     }
                 }
+            }
+        }
 
         /* Declare user activity.
          This wakes the display if it is off, and postpones display sleep according to the users system preferences