问题
WhatsApp now saves pictures to a custom folder named "WhatsApp" in the media library. Is WhatsApp using a undocumented API or is this possible for every developer? Right now I am only aware of the possibility to save pictures to the "Camera Roll" or to the "Saved Pictures".
回答1:
It appears WhatsApp has special permission to do that as no current APIs for Windows Phone 8 (with GDR3) allow you to specify a folder name.
The hope is that Windows Phone 8.1 will introduce new APIs for both saving pictures and video.
来源：https://stackoverflow.com/questions/20757538/save-pictures-to-custom-folder-in-media-library