今是昨非

    func setupAudioSession() {
        do {
            // .notifyOthersOnDeactivationを設定し、Activeがfalseのときに有効になり、システムに本アプリの再生が終了したことを通知し、他のアプリの再生を続けることができます
            try AVAudioSession.sharedInstance().setActive(true, options: AVAudioSession.SetActiveOptions.notifyOthersOnDeactivation)
            
            // 実際のニーズに応じて異なるCategoryを切り替えます
            try AVAudioSession.sharedInstance().setCategory(AVAudioSession.Category.playback, options: AVAudioSession.CategoryOptions.duckOthers)
        } catch {
            print("set AudioSession error: %@", error)
        }
    }

#import <MediaPlayer/MPNowPlayingInfoCenter.h>
#import <MediaPlayer/MPRemoteCommandCenter.h>
#import <MediaPlayer/MPRemoteCommand.h>
#import <MediaPlayer/MPMediaItem.h>

// 通知バー表示を更新
- (void)updateNowPlaingInfo {
    NSMutableDictionary *dict = [NSMutableDictionary dictionary];
    // 曲のタイトルを設定
    [dict setValue:@"タイトル" forKey:MPMediaItemPropertyTitle];
    // アーティスト名を設定
    [dict setValue:@"アーティスト" forKey:MPMediaItemPropertyArtist];
    // アルバム名を設定
    [dict setValue:@"アルバムタイトル" forKey:MPMediaItemPropertyAlbumTitle];
    // 表示する画像を設定
    MPMediaItemArtwork *artwork = [[MPMediaItemArtwork alloc] initWithImage:ArtImage];
    [dict setValue:artwork forKey:MPMediaItemPropertyArtwork];
    // 曲の長さを設定
    NSTimeInterval duration = self.player.duration;
    [dict setValue:[NSNumber numberWithDouble:duration] forKey:MPMediaItemPropertyPlaybackDuration];
    // すでに再生された長さを設定
    NSTimeInterval currentTime = self.player.currentTime;
    [dict setValue:[NSNumber numberWithDouble:currentTime] forKey:MPNowPlayingInfoPropertyElapsedPlaybackTime];
    // 再生速度を設定
    [dict setValue:@(1.0) forKey:MPNowPlayingInfoPropertyPlaybackRate];
    
    // 更新
    [[MPNowPlayingInfoCenter defaultCenter] setNowPlayingInfo:dict];
}

    [[MPNowPlayingInfoCenter defaultCenter] setNowPlayingInfo:@{}];

// AppDelegate内、または対応する再生のController内で、システム制御イベントの受信を開始します
// システム制御イベントを受信
[[UIApplication sharedApplication] beginReceivingRemoteControlEvents];
[self becomeFirstResponder];

- (void)setupCommandCenter {
    MPRemoteCommandCenter *commandCenter = [MPRemoteCommandCenter sharedCommandCenter];
    [commandCenter.playCommand removeTarget:self];
    [commandCenter.pauseCommand removeTarget:self];
    
    // 前の曲、次の曲を無効にします
    commandCenter.previousTrackCommand.enabled = NO;
    commandCenter.nextTrackCommand.enabled = NO;
    
    // 再生
    commandCenter.playCommand.enabled = YES;
    
    // 一時停止
    commandCenter.pauseCommand.enabled = YES;
    
    // 再生と一時停止（ヘッドフォン制御）
    commandCenter.togglePlayPauseCommand.enabled = NO;

    // 進行状況をドラッグ
    commandCenter.changePlaybackPositionCommand.enable = YES;
}

// リモートイベントに応答
- (void)remoteControlReceivedWithEvent:(UIEvent *)event {
    if (event.type == UIEventTypeRemoteControl) {
        switch (event.subtype) {
            case UIEventSubtypeRemoteControlPlay:
            {
                NSLog(@"RemoteControlEvents: 再生");
            }
                break;
            case UIEventSubtypeRemoteControlPause:
            {
                NSLog(@"RemoteControlEvents: 一時停止");
            }
                break;
            case UIEventSubtypeRemoteControlTogglePlayPause:
                NSLog(@"ヘッドフォン制御：一時停止||再生");
                break;
            case UIEventSubtypeRemoteControlNextTrack:
            {
                NSLog(@"RemoteControlEvents: 次の曲");
            }
                break;
            case UIEventSubtypeRemoteControlPreviousTrack:
            {
                NSLog(@"RemoteControlEvents: 前の曲");
            }
                break;
            default:
                break;
        }
    }
}

- (void)setupCommandCenter {
    MPRemoteCommandCenter *commandCenter = [MPRemoteCommandCenter sharedCommandCenter];

    // 再生
    [commandCenter.playCommand addTargetWithHandler:^MPRemoteCommandHandlerStatus(MPRemoteCommandEvent * _Nonnull event) {
        NSLog(@"再生");
        return MPRemoteCommandHandlerStatusSuccess;
    }];

    // 一時停止
    [commandCenter.pauseCommand addTarget:self action:@selector(handlePauseCommand:)];

    // 進行状況をドラッグ
    [commandCenter.changePlaybackPositionCommand addTarget:self action:@selector(handlePlaybackPositionCommand:)];
}

- (MPRemoteCommandHandlerStatus):(id)sender {
    NSLog(@"一時停止");
    return MPRemoteCommandHandlerStatusSuccess;
}

- (MPRemoteCommandHandlerStatus)handlePlaybackPositionCommand:
(MPChangePlaybackPositionCommandEvent *) event

{
    [self.palyer seekToTime:CMTimeMakeWithSeconds(event.positionTime, 1)];

    NSLog(@"changePlaybackPosition to %f", event.positionTime);

    return MPRemoteCommandHandlerStatusSuccess;
}