首先，有

import MobileCoreServices

let imagepicker = UIImagePickerController()

imagepicker.mediaTypes = [ String(kUTTypeMovie) ] 用kUTTypeMoive已经不推荐了，而且也不推荐这种写法。

警告：'kUTTypeMovie' was deprecated in xrOS 1.0: Use UTTypeMovie or UTType.movie (swift) instead.

根据警告，如果直接赋值

imagepicker.mediaTypes = [ String(UTType.movie) ]  或者

imagepicker.mediaTypes = [UTType.movie as String] 都有问题的。

前者出错：No exact matches in call to initializer 

后者出错：Cannot convert value of type 'UTType' to type 'String' in coercion

主要UTType是结构体，牛头不对马嘴。

正确写法：

imagepicker.mediaTypes = [UTType.movie.identifier]