Add Swift Package Manager support

Author: dreampiggy

.gitignore

@@ -62,4 +62,8 @@ fastlane/test_output
 # After new code Injection tools there's a generated folder /iOSInjectionProject
 # https://github.com/johnno1962/injectionforxcode
 
-iOSInjectionProject/
+iOSInjectionProject/
+
+# SwiftPM
+.swiftpm
+.build

Package.resolved

@@ -0,0 +1,16 @@
+{
+  "object": {
+    "pins": [
+      {
+        "package": "libde265",
+        "repositoryURL": "https://github.com/SDWebImage/libde265-Xcode.git",
+        "state": {
+          "branch": null,
+          "revision": "39b0430c631669dba8e578a2ececae3a05dbb935",
+          "version": "1.0.4"
+        }
+      }
+    ]
+  },
+  "version": 1
+}

Package.swift

@@ -0,0 +1,33 @@
+// swift-tools-version:5.0
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import PackageDescription
+
+let package = Package(
+    name: "libheif",
+    products: [
+        // Products define the executables and libraries produced by a package, and make them visible to other packages.
+        .library(
+            name: "libheif",
+            targets: ["libheif"]),
+    ],
+    dependencies: [
+        // Dependencies declare other packages that this package depends on.
+        .package(url: "https://github.com/SDWebImage/libde265-Xcode.git", from: "1.0.4")
+    ],
+    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: "libheif",
+            dependencies: ["libde265"],
+            path: ".",
+            exclude: ["libheif/libheif/box_fuzzer.cc", "libheif/libheif/color_conversion_fuzzer.cc", "libheif/libheif/encoder_fuzzer.cc", "libheif/libheif/file_fuzzer.cc", "libheif/libheif/heif_encoder_x265.h", "libheif/libheif/heif_encoder_x265.cc"],
+            sources: ["libheif/libheif"],
+            publicHeadersPath: "include",
+            cSettings: [.define("HAVE_UNISTD_H"), .define("HAVE_LIBDE265")]
+        )
+    ],
+    cLanguageStandard: .gnu11,
+    cxxLanguageStandard: .gnucxx14
+)