Swift Package Manager: dependency iOS version

Question

I'm trying to build swift package with external dependency (CoreStore) with xCode11 beta 7. My package is targeted for iOS11+, it's declared in Package.swift:

// swift-tools-version:5.1
// The swift-tools-version declares the minimum version of Swift required to build this package.

import PackageDescription

let package = Package(
    name: "Storages",
    platforms: [.iOS(.v11)],
    products: [
        // Products define the executables and libraries produced by a package, and make them visible to other packages.
        .library(
            name: "Storages",
            targets: ["Storages"]),
    ],
    dependencies: [
        // Dependencies declare other packages that this package depends on.
        .package(url: "https://github.com/JohnEstropia/CoreStore.git", from: "6.3.0")
    ],
    targets: [
        // Targets are the basic building blocks of a package. A target can define a module or a test suite.
        // Targets can depend on other targets in this package, and on products in packages which this package depends on.
        .target(
            name: "Storages",
            dependencies: [.product(name: "CoreStore")]),

        .testTarget(
            name: "StoragesTests",
            dependencies: ["Storages"]),
    ]
)

However, when I build it dependency builds without iOS version specified, so I get compatibility errors: "'uniquenessConstraints' is only available in iOS 9.0 or newer" and so on.

How can I fix it? Looks like it's xCode11 bug, but I'm not sure.

Answer 1

On my machine, adding the platforms: parameter to the manifest solved it. For example:

let package = Package(
    name: "MyLibrary",
    platforms: [.iOS("13.0")],
    // ...

Answer 2

I'm not sure is it xCode bug or not, however with Swift Package Manager and xCode 11 you have to clearly specify iOS version when use #available check. Not matter if library is targeted for iOS 10+ or not, instead of

if #available(macOS 10.11, *) {
    info.append(("uniquenessConstraints", self.uniquenessConstraints))
}

you should use

if #available(macOS 10.11, iOS 9.0, *) {
    info.append(("uniquenessConstraints", self.uniquenessConstraints))
}

Pull request was posted: https://github.com/JohnEstropia/CoreStore/pull/341