VLCMediaPlayerDelegate: fix protocol declaration and drop unneeded casts

Headers/Public/VLCMediaPlayer.h

@@ -97,7 +97,7 @@ extern NSString * VLCMediaPlayerStateToString(VLCMediaPlayerState state);
  * Formal protocol declaration for playback delegates.  Allows playback messages
  * to be trapped by delegated objects.
  */
-@protocol VLCMediaPlayerDelegate
+@protocol VLCMediaPlayerDelegate <NSObject>
 
 @optional
 /**

Sources/VLCMediaPlayer.m

@@ -1554,12 +1554,12 @@ static void HandleMediaPlayerRecord(const libvlc_event_t * event, void * self)
     BOOL isRecording = [arguments.firstObject[@"isRecording"] boolValue];
 
     if (isRecording) {
-        if ([(NSObject *)_delegate respondsToSelector:@selector(mediaPlayerStartedRecording:)]) {
+        if ([_delegate respondsToSelector:@selector(mediaPlayerStartedRecording:)]) {
             [_delegate mediaPlayerStartedRecording:self];
         }
     } else {
-        if ([(NSObject *)_delegate respondsToSelector:@selector(mediaPlayer:recordingStoppedAtPath:)]) {
-            [self.delegate mediaPlayer:self recordingStoppedAtPath:filePath];
+        if ([_delegate respondsToSelector:@selector(mediaPlayer:recordingStoppedAtPath:)]) {
+            [_delegate mediaPlayer:self recordingStoppedAtPath:filePath];
         }
     }
 }