Using the framework by the Swift Package Manager result in a build error on Xcode 11 (but probably also on Xcode 10.2). The reason is because in the Package.swift, line 21 there is
swiftLanguageVersions: [.v4]
While the used version of swift is 4.2. To support build should be changed in
swiftLanguageVersions: [.v4_2, .v5]
I also did a quick test of using GPUImage3 with Swift Package Manager.
Some compile errors pop up related to swift version.
So I guess @GiacomoLeopizzi is right.
Using the framework by the Swift Package Manager result in a build error on Xcode 11 (but probably also on Xcode 10.2). The reason is because in the Package.swift, line 21 there is
swiftLanguageVersions: [.v4]
While the used version of swift is 4.2. To support build should be changed inswiftLanguageVersions: [.v4_2, .v5]