Add an iPhone client sharing the macOS app's SwiftUI code

mac/Sources/Byre/BoxDiagram.swift

@@ -1,4 +1,3 @@
-import AppKit
 import CoreText
 import SwiftUI
 
@@ -280,17 +279,17 @@ private let margin: CGFloat = 20
 
 @MainActor
 private var titleFont: CTFont {
-    Fonts.ns(13, weight: 600) as CTFont
+    Fonts.native(13, weight: 600) as CTFont
 }
 
 @MainActor
 private var detailFont: CTFont {
-    Fonts.ns(12) as CTFont
+    Fonts.native(12) as CTFont
 }
 
 @MainActor
 private var edgeLabelFont: CTFont {
-    Fonts.ns(11) as CTFont
+    Fonts.native(11) as CTFont
 }
 
 @MainActor
@@ -953,6 +952,7 @@ private struct TappableCanvas: View {
     }
 }
 
+#if os(macOS)
 private final class CenteringClipView: NSClipView {
     override func constrainBoundsRect(_ proposedBounds: NSRect) -> NSRect {
         var r = super.constrainBoundsRect(proposedBounds)
@@ -1007,3 +1007,62 @@ private struct ZoomingCanvas: NSViewRepresentable {
         (scroll.documentView as? NSHostingView<TappableCanvas>)?.rootView = TappableCanvas(layout: layout, focus: focus, tap: tap)
     }
 }
+#else
+private final class FittingScrollView: UIScrollView, UIScrollViewDelegate {
+    let host: UIHostingController<TappableCanvas>
+    private var fitted = false
+
+    init(_ canvas: TappableCanvas, size: CGSize) {
+        host = UIHostingController(rootView: canvas)
+        super.init(frame: .zero)
+        host.view.backgroundColor = .clear
+        host.view.frame = CGRect(origin: .zero, size: size)
+        addSubview(host.view)
+        contentSize = size
+        delegate = self
+        minimumZoomScale = 0.25
+        maximumZoomScale = 6
+    }
+
+    required init?(coder: NSCoder) {
+        fatalError("init(coder:) is not supported")
+    }
+
+    override func layoutSubviews() {
+        super.layoutSubviews()
+        if !fitted, bounds.width > 0, bounds.height > 0, host.view.bounds.width > 0 {
+            fitted = true
+            zoomScale = min(2, bounds.width / host.view.bounds.width, bounds.height / host.view.bounds.height)
+        }
+        center()
+    }
+
+    func viewForZooming(in scrollView: UIScrollView) -> UIView? {
+        host.view
+    }
+
+    func scrollViewDidZoom(_ scrollView: UIScrollView) {
+        center()
+    }
+
+    private func center() {
+        let x = max(0, (bounds.width - contentSize.width) / 2)
+        let y = max(0, (bounds.height - contentSize.height) / 2)
+        contentInset = UIEdgeInsets(top: y, left: x, bottom: y, right: x)
+    }
+}
+
+private struct ZoomingCanvas: UIViewRepresentable {
+    let layout: BoxLayout
+    let focus: BoxFocus?
+    let tap: (String?) -> Void
+
+    func makeUIView(context: Context) -> FittingScrollView {
+        FittingScrollView(TappableCanvas(layout: layout, focus: focus, tap: tap), size: layout.size)
+    }
+
+    func updateUIView(_ scroll: FittingScrollView, context: Context) {
+        scroll.host.rootView = TappableCanvas(layout: layout, focus: focus, tap: tap)
+    }
+}
+#endif