iOS 下无法开启硬解码，输出显示没有开启 VideoToolbox

**这次的测试设备室` iPhone6Plus`，系统` iOS 11.3`，解码的是远程` rtsp `流，设置过了` rtsp-tcp`。**
**我按照**`[options setPlayerOptionIntValue:1 forKey:@"videotoolbox"];`**的方式设置过，但是不能正常播放，提示**
```
2018-07-04 16:29:54.856117+0800 ijkplayer-ios-test[573:58987] FFP_MSG_FIND_STREAM_INFO:
aout_open_audio()
aout_pause_audio(0)
vtbformat_init - using avcC atom of size(65), ref_frames(0)m_max_ref_frames 2
vtbformat_init - using avcC atom of size(65), ref_frames(2)m_max_ref_frames 2
after scale width 2560 height 1600
```
**关闭`videotoolbox`设置之后就能正常解码和播放。**
**求大神解答，谢谢了。**

Start by reproducing the issue on the stated iPhone 6 Plus and iOS 11.3 setup with the remote RTSP stream and the `videotoolbox` option enabled through `setPlayerOptionIntValue`. Compare the logged VideoToolbox initialization with playback after disabling the option; done means the cause is identified and hardware decoding works for the reported stream.

Written by the indexing model from the issue text.