Add NSViewRepresentable for AppKit & support Swift 6 concurrency.

Package.swift

@@ -95,7 +95,7 @@ let package = Package(
         ),
         .package(
             url: "https://github.com/stackotter/swift-image-formats",
-            .upToNextMinor(from: "0.3.1")
+            .upToNextMinor(from: "0.3.2")
         ),
         .package(
             url: "https://github.com/wabiverse/swift-windowsappsdk",

Sources/AppKitBackend/BaseWidget.swift

@@ -0,0 +1,123 @@
+import AppKit
+
+public class BaseWidget: NSView {
+    private var leftConstraint: NSLayoutConstraint?
+    private var topConstraint: NSLayoutConstraint?
+    private var widthConstraint: NSLayoutConstraint?
+    private var heightConstraint: NSLayoutConstraint?
+
+    var x = 0 {
+        didSet {
+            if x != oldValue {
+                updateLeftConstraint()
+            }
+        }
+    }
+
+    var y = 0 {
+        didSet {
+            if y != oldValue {
+                updateTopConstraint()
+            }
+        }
+    }
+
+    var width = 0 {
+        didSet {
+            if width != oldValue {
+                updateWidthConstraint()
+            }
+        }
+    }
+
+    var height = 0 {
+        didSet {
+            if height != oldValue {
+                updateHeightConstraint()
+            }
+        }
+    }
+
+    init() {
+        super.init(frame: .zero)
+
+        self.translatesAutoresizingMaskIntoConstraints = false
+    }
+
+    @available(*, unavailable)
+    public required init?(coder: NSCoder) {
+        fatalError("init(coder:) is not used for this view")
+    }
+
+    private func updateLeftConstraint() {
+        leftConstraint?.isActive = false
+        guard let superview else { return }
+        if #available(macOS 11.0, *) {
+            leftConstraint = self.leftAnchor.constraint(
+                equalTo: superview.safeAreaLayoutGuide.leftAnchor, constant: CGFloat(x))
+        } else {
+            leftConstraint = self.leftAnchor.constraint(
+                equalTo: superview.leftAnchor, constant: CGFloat(x))
+        }
+        leftConstraint!.isActive = true
+    }
+
+    private func updateTopConstraint() {
+        topConstraint?.isActive = false
+        guard let superview else { return }
+        if #available(macOS 11.0, *) {
+            topConstraint = self.topAnchor.constraint(
+                equalTo: superview.safeAreaLayoutGuide.topAnchor, constant: CGFloat(x))
+        } else {
+            topConstraint = self.topAnchor.constraint(
+                equalTo: superview.topAnchor, constant: CGFloat(x))
+        }
+        topConstraint!.isActive = true
+    }
+
+    private func updateWidthConstraint() {
+        widthConstraint?.isActive = false
+        widthConstraint = self.widthAnchor.constraint(equalToConstant: CGFloat(width))
+        widthConstraint!.isActive = true
+    }
+
+    private func updateHeightConstraint() {
+        heightConstraint?.isActive = false
+        heightConstraint = self.heightAnchor.constraint(equalToConstant: CGFloat(height))
+        heightConstraint!.isActive = true
+    }
+
+    public override func viewDidMoveToSuperview() {
+        super.viewDidMoveToSuperview()
+
+        updateLeftConstraint()
+        updateTopConstraint()
+    }
+}
+
+class WrapperWidget<View: NSView>: BaseWidget {
+    init(child: View) {
+        super.init()
+
+        self.addSubview(child)
+        child.translatesAutoresizingMaskIntoConstraints = false
+        NSLayoutConstraint.activate([
+            child.topAnchor.constraint(equalTo: self.topAnchor),
+            child.leadingAnchor.constraint(equalTo: self.leadingAnchor),
+            child.bottomAnchor.constraint(equalTo: self.bottomAnchor),
+            child.trailingAnchor.constraint(equalTo: self.trailingAnchor),
+        ])
+    }
+
+    override convenience init() {
+        self.init(child: View(frame: .zero))
+    }
+
+    var child: View {
+        subviews[0] as! View
+    }
+
+    override var intrinsicContentSize: CGSize {
+        child.intrinsicContentSize
+    }
+}