Cocoa Touch Framework - is an iOS framework, SwiftPM currently doesn't support iOS.
Here is a quote from Swift Package Manager Readme
Note that at this time the Package Manager has no support for iOS, watchOS, or tvOS platforms.
But it will be supported in the future. You can read more about it here - Swift Package Manager 3.0 Project Status
If you want to make iOS framework you can run swift package generate-xcodeproj and change the framework target to iOS. You can also pass custom .xcconfig file with a custom configurations
swift package generate-xcodeproj --xcconfig-overrides Configs.xcconfig