example/swift-package: add Swift Package Manager example

This depends on #70 (golang.org/cl/334689).

Author: ydnar

example/swift-package/Makefile

@@ -0,0 +1,17 @@
+.DEFAULT: build
+
+build: Frameworks $(wildcard Package.*) $(wildcard Sources/*/*)
+	swift build -c release
+
+.PHONY: Frameworks
+Frameworks: Frameworks/GetGo.xcframework
+
+Frameworks/%.xcframework: Makefile $(wildcard Sources/*/*.go) $(shell which gomobile)
+	mkdir -p Frameworks
+	gomobile init
+	gomobile bind -target=ios,iossimulator,macos,maccatalyst -x -o $@ ./Sources/$*
+	touch $@
+
+test: build
+	go test ./...
+	swift test

example/swift-package/Package.swift

@@ -0,0 +1,25 @@
+// swift-tools-version:5.3
+import PackageDescription
+
+let package = Package(
+	name: "GetKit",
+	products: [
+		.library(
+			name: "GetKit",
+			targets: ["GetGo"]
+		),
+	],
+	targets: [
+		.target(
+			name: "GetKit"
+		),
+		.binaryTarget(
+			name: "GetGo",
+			path: "Frameworks/GetGo.xcframework"
+		),
+		.testTarget(
+			name: "GetKitTests",
+			dependencies: ["GetKit", "GetGo"]
+		),
+	]
+)

example/swift-package/README.md

@@ -0,0 +1,13 @@
+# [gomobile](https://pkg.go.dev/golang.org/x/mobile/cmd/gomobile) + [Swift Package Manager](https://swift.org/package-manager/)
+
+Example [Go](https://golang.org/) package built into an [XCFramework](https://developer.apple.com/documentation/swift_packages/distributing_binary_frameworks_as_swift_packages) for [Swift Package Manager](https://swift.org/package-manager/), targeting iOS, macOS, and macCatalyst targets.
+
+## Requirements
+
+Go 1.16, Swift 5.3, and Xcode 11 or later.
+
+## Usage
+
+To build the XCFramework and Swift package: `make build`
+
+To test: `make test`

example/swift-package/Sources/GetGo/get.go

@@ -0,0 +1,22 @@
+package Go
+
+import (
+	"io"
+	"net/http"
+)
+
+// Get makes an HTTP(S) GET request to url,
+// returning the resulting content or an error.
+func Get(url string) ([]byte, error) {
+	res, err := http.Get(url)
+	if err != nil {
+		return nil, err
+	}
+	defer res.Body.Close()
+	return io.ReadAll(res.Body)
+}
+
+// Version returns the version string for this package.
+func Version() string {
+	return "0.0.1"
+}

example/swift-package/Sources/GetKit/GetKit.swift

@@ -0,0 +1 @@
+// Stub file so Swift Package Manager doesn’t complain

example/swift-package/Tests/GetKitTests/GetTest.swift

@@ -0,0 +1,27 @@
+import XCTest
+
+@testable import GetGo
+
+class GetTests: XCTestCase {
+	func testGet() {
+		var error: NSErrorPointer = nil
+		let response = GoGet("https://golang.org/", error)
+		XCTAssertNil(error)
+		guard let response = response else {
+			XCTFail("response == nil")
+			return
+		}
+		guard let str = String(data: response, encoding: .utf8) else {
+			XCTFail("str == nil")
+			return
+		}
+		XCTAssert(str.contains("Go"))
+		XCTAssert(str.contains("an open source programming language"))
+		XCTAssert(str.contains("https://play.golang.org"))
+	}
+
+	func testVersion() {
+		let version = GoVersion()
+		XCTAssertEqual(version, "0.0.1")
+	}
+}