Xcode 6:如何让图像视图在所有设备上填充屏幕?自动布局不工作吗?

So I have an image view and a button. I need the image view to be the correct size (not look squished or stretched) on all devices and more importantly I need it to be the size of the screen. I need the button to stay in about the same place on all devices. So I have an image view and a button. I need th