Add Swift Package Manager support

.swiftpm/xcode/package.xcworkspace/contents.xcworkspacedata

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Workspace
+   version = "1.0">
+   <FileRef
+      location = "self:">
+   </FileRef>
+</Workspace>

Package.resolved

@@ -0,0 +1,16 @@
+{
+  "object": {
+    "pins": [
+      {
+        "package": "SDWebImage",
+        "repositoryURL": "https://github.com/SDWebImage/SDWebImage.git",
+        "state": {
+          "branch": null,
+          "revision": "0a3cd255a655b73fb3b3437acf2ab506b5c0c9c6",
+          "version": "5.1.0"
+        }
+      }
+    ]
+  },
+  "version": 1
+}

Package.swift

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+// 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: "SDWebImageSwiftUI",
+    platforms: [
+       .macOS(.v10_15), .iOS(.v13), .tvOS(.v13), .watchOS(.v6)
+    ],
+    products: [
+        // Products define the executables and libraries produced by a package, and make them visible to other packages.
+        .library(
+            name: "SDWebImageSwiftUI",
+            targets: ["SDWebImageSwiftUI"]),
+    ],
+    dependencies: [
+        // Dependencies declare other packages that this package depends on.
+        // .package(url: /* package url */, from: "1.0.0"),
+        .package(url: "https://github.com/SDWebImage/SDWebImage.git", from: "5.1.0")
+    ],
+    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: "SDWebImageSwiftUI",
+            dependencies: ["SDWebImage"],
+            path: "SDWebImageSwiftUI/Classes"),
+    ]
+)