Application can’t be opened» for the app built in XCode

You need to provide more information.

Have you checked the system log? (Console app)

What does your app do? (brief description, resources used, etc.)

Where is the app installed? (system application folder or user application folder)

Have you tried running your app as a brand new user? (your problem appears to be environmental)

What is the setting of system preferences -> security and privacy -> allow apps downloaded from?

Let me be clear. I've never programmed in Swift.

That said, I've read your code and the following line indicates that your program depends on a resource.

let url = URL(string: "http://obukhow.ru/oggetto/gaetano-api.php")!

If the resource is not available to a user what will the program do?

Here is a link to swift code that might be of use

https://www.swiftbysundell.com/posts/constructing-urls-in-swift

Specifically, constructing a URL extension called staticString and then using as follows

let url = URL(staticString: "http://obukhow.ru/oggetto/gaetano-api.php")

replacing the above line.

Hope this helps

I'm thinking the use of "guard" is important here, not necessarily "preconditionFailure".

You need to "guard" against an invalid URL instance prior to using it.