ios11，在rootviewcontroller中初始化player，会无法显示图像，只有声音

ios11，在刚启动的rootviewcontroller中初始化player，会无法显示图像，只有声音，然后按home前后切换下，又有图像了。如果player不是在刚启动的viewcontroller中初始化的，那么能够正常播放，有图片和声音

Start by reproducing playback when the player is initialized in the app's initial root view controller on iOS 11, then compare it with initialization in a later view controller and with switching away and back using Home. Trace the root-view-controller and player initialization paths; done means video is visible immediately while audio continues to play.

Written by the indexing model from the issue text.