//NavigationBar的title顏色改變代碼：
[self.navigationController.navigationBar setTitleTextAttributes:@{NSFontAttributeName:[UIFont systemFontOfSize:19],NSForegroundColorAttributeName:[UIColor whiteColor]}];
//使navigationController的背景顏色為白色

1. //放在最下面（放一個uiview在上面）
   UIView *navigView = [[UIView alloc]initWithFrame:CGRectMake(0, 0, kWidth, 64)];
   navigView.backgroundColor = [UIColor colorWithWhite:0 alpha:0.3];
   [self.view addSubview:navigView];
2. //隱藏半透明度
   self.navigationController.navigationBar.translucent = YES;
   self.navigationController.navigationBar.shadowImage = [[UIImage alloc]init];
   [self.navigationController.navigationBar setBackgroundImage:[[UIImage alloc]init] forBarMetrics:UIBarMetricsDefault];
3. // fileDuration位置應該是一個為double類型的歌曲時長秒數
   //時間類型
   NSDate *date = [[NSDate alloc] initWithTimeIntervalSince1970:fileDuration];
   NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
   if (fileDuration >= 3600) {
   [formatter setDateFormat:@"HH:mm:ss"];
   } else {
   [formatter setDateFormat:@"mm:ss"];
   }
   NSString *dateStr = [formatter stringFromDate:date];