到目前为止，目前尚无法访问设备的墙纸.

There is no way to currently access the device's Wallpaper as of now.

尽管越狱的设备可以访问此功能，但从本质上讲，Apple不允许这样做.

Essentially Apple doesn't allow it, though jailbroken devices can access this functionality.

也不允许您在第三方应用中设置或更改整个手机的墙纸.用户必须通过设置或照片应用程序手动执行此操作.您可以添加有关用户如何在您的应用程序中执行此操作的说明.

You also aren't allowed to set or change the wallpaper of the entire phone in third party apps. The user has to do that manually through the settings or photos app. You can add instructions as to how the user can do that in your app.