Iphone 为什么链接器在构建我的应用程序时显示有关MPMoviePlayerController的错误？

构建时，我在链接阶段收到此错误：

      ".objc_class_name_MPMoviePlayerController", referenced from:
          literal-pointer@__OBJC@__cls_refs@MPMoviePlayerController in MovieDemoViewController.o
      "_MPMoviePlayerPlaybackDidFinishNotification", referenced from:
          _MPMoviePlayerPlaybackDidFinishNotification$non_lazy_ptr in MovieDemoViewController.o
    ld: symbol(s) not found
    collect2: ld returned 1 exit status
Build failed (2 errors)

为什么会发生这种情况？

导入

#import <MediaPlayer/MediaPlayer.h>

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您可能忘了链接MediaPlayer框架。右键单击项目，然后选择添加|现有框架。。。菜单项。从该列表中选择MediaPlayer框架。

我的头文件中没有这个文件/hi friendz的可能副本告诉我如何将视频文件保存到iphone