bgMusic.onTimeUpdate(() => {
      console.log(bgMusic.duration);
      const mate = (bgMusic.currentTime / bgMusic.duration) * 100;
      console.log(mate);
      const currentPlayNode = _getCurrentPlayNode();
      console.log(currentPlayNode);
      currentPlayNode.setData({
          offset: mate
      });
  });

就这段代码，开发工具上运行OK，但是在真机iOS上，duration一直是输出0？

是bug么