View controller showing no content

Question

I'm new to iOS and is trying out the beginner's project of building a calculator. This is where I'm up to:

I don't know what I did but suddenly the view control panel turned into a blank panel:

I can't get the original panel back. I have clicked pretty much everything and still can't get it back.

Answer 1

单击情节提要，然后尝试使用ctrl + z 恢复“上一步”或上载演示。

Answer 2

如果您使用的是导航控制器，能否请您确认是否为主控制器和rootview控制器提供了正确的入口点。

Answer 3

I guess you might have pressed "LaunchScreen.storyboard" instead of "Main.storyboard" accidentally. Do check that !