This error message is informing the developer that the UIKit framework cannot be used when building an application for macOS. UIKit is a framework only available for iOS app development, and macOS has its own set of frameworks that should be used instead.
To solve this issue, the developer should use conditional compilation to check if the code is being built for macOS or not. If it is being built for macOS, then the developer should use the appropriate frameworks.
Here is an example of how to use conditional compilation to import the appropriate framework:
#if !os(macOS)
import UIKit
#else
import AppKit
#endif
This code checks if the app is being built for macOS or not by using the !os(macOS) condition. If it is being built for macOS, then the code imports the AppKit framework instead of UIKit. This way, the developer can ensure that the correct framework is being used based on the platform.