获取当前未打开的ViewController的屏幕截图

I am writing an app in Swift. In my app, I have a ViewController. There is a button on it, as well as an image view. When I press that button, I need to take a screenshot of another ViewController, have all the constraints that I defined in Interface Builder for the second ViewController work, and the code in view did load run. I then will put the ScreenShot in the image view. I found this thread I am writing an app in Swift. In my app, I have