事实证明，无论我是否删除了应用程序，物理设备都会缓存图像.唯一有效的方法是1.删除应用程序，然后2.重新启动设备.只有这样，图像才会消失.从iOS 9.2开始不知道这是否是一个错误

Turns out that the physical device caches the images regardless if i removed the application or not. The only thing that actually worked was to 1. Remove the application and 2. Reboot the device. Only then the images would disappear. Don't know if this is a bug or not as of iOS 9.2