Switch demonstration application dependency from Carthage to SPM

[pyby]

Issue type

Feature request

Description of the problem

Since #257, the make setup builds all AppCenter frameworks, for iOS and tvOS platforms. it takes time, and not all libraries are needed (like no AppCenterAnalytics.

The idea is to switch to SPM dependency, as it's the dependency tool used for all SRG libraries.

The goal is to:

• keep the single and universal target: see Demo.xcconfig and https://davedelong.com/blog/2018/11/15/building-a-crossplatform-framework/
• keep AppCenterDistribute dependency optional: only for iOS build, not for tvOS build.

Environment information

• Package Manager Conditional Target Dependencies in Swift 5.3.

[pyby]

Sadly, the Xcode UI option to filter platform in the general target tab, "Frameworks, Libraries, and Content" section is only use during the link build phases.

When selected an Apple TV destination, Xcode tries to build AppCenterDistribute library. The build fails, as the target is not available for tvOS.

Swift 5.3 introduced the Package Manager Conditional Target Dependencies (SE-0273). It's only for dependencies. Xcode SPM integration seems to not have this optional option for a dependency per platform.

[pyby]

We got a workaround idea: create an empty local product, which create the optional dependency on AppCenterDistribute.

A AppCenterDistributeOptional library is proposed. Naming can be discussed. This workaround works.

Proposition is on feature/remove-carthage branch.