音乐应用可以更改锁屏壁纸，因为iOS会自动显示歌曲的专辑图片/正在播放的播客/等（参见 MPMusicPlayerController docs ）。据我所知，它不是开发人员公开可用的API。

Music apps can change the lock screen wallpaper because iOS automatically displays the album artwork for the song/podcast/etc that's playing (see MPMusicPlayerController docs). As far as I know, it's not an API that's publicly available to developers.