ios – The way to resolve error the place renaming struct causes errors for timer app in swift?

I’m attempting to create a timer that counts down so I can implement it to a app I’m creating, here’s a demo challenge:
https://www.dropbox.com/scl/fo/h6uggyqzpwhxji76dv4ck/h?rlkey=5an6cwpshyft1f9q0y8p8gvk0&dl=0

The error I’m dealing with is that after I change the struct identify to one thing different then ContentView() I get this error:

Error after I rename struct

But when the struct is ContentView() I get no error:

No error when struct identify ContentView

What can I achieve this I can identify the struct one thing different then ContentView() and never get any errors (Like if I need to identify the struct Timer() what ought to I do)?

Thanks upfront,

I attempted to make use of a unique timer technique however couldn’t discover/perceive any as I’m new to swift.