Add UIKit SupportHEAD1.1.0main

3 files changed, 120 insertions, 2 deletions

diff --git a/README.md b/README.md
index dc8cec4..9819fd0 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,7 @@
 # Norg Keyboard Toolbar
 
 This package provides a toolbar you can use whenever you need to edit norg
-files. The toolbar provides the following buttons:
+files in SwiftUI or UIKit apps. The toolbar provides the following buttons:
 
 The heading button creates a new heading, or increases the heading of the
 current level. See this table for examples.
@@ -30,6 +30,8 @@ The code button adds a `@code` and `@end` block.
 
 ## Usage
 
+### SwiftUI
+
 Add the package to your project by including the repo URL with Xcode's package
 manager, and import it:
 
@@ -54,6 +56,24 @@ struct EditorView: View {
 of the screen if a hardware keyboard is connected.) with the buttons described
 above.
 
+### UIKit
+
+Add the package to your project by including the repo URL with Xcode's package
+manager, and import it:
+
+```swift
+import UIKit
+import NorgKeyboardToolbar
+
+...
+
+let textView = UITextView()
+textView.installNorgKeyboardAccessory()
+```
+
+`installNorgKeyboardAccessory` then attaches a toolbar above the keyboard with
+the buttons described above.
+
 ## Development
 
 A `Justfile` is provided to run common tasks:
diff --git a/Sources/NorgKeyboardToolbar/EditorSnippet.swift b/Sources/NorgKeyboardToolbar/EditorSnippet.swift
index 4773eac..fe0a469 100644
--- a/Sources/NorgKeyboardToolbar/EditorSnippet.swift
+++ b/Sources/NorgKeyboardToolbar/EditorSnippet.swift
@@ -1,7 +1,7 @@
 import Foundation
 
 /// The available editor snippets to show in the toolbar.
-enum EditorSnippet: String, CaseIterable, Identifiable, Sendable {
+public enum EditorSnippet: String, CaseIterable, Identifiable, Sendable {
   case heading
   case task
   case weakReverse
diff --git a/Sources/NorgKeyboardToolbar/NorgKeyboardAccessory.swift b/Sources/NorgKeyboardToolbar/NorgKeyboardAccessory.swift
new file mode 100644
index 0000000..3538330
--- /dev/null
+++ b/Sources/NorgKeyboardToolbar/NorgKeyboardAccessory.swift
@@ -0,0 +1,98 @@
+#if canImport(UIKit)
+  import UIKit
+
+  // MARK: - Applying snippets to a UITextView
+
+  extension EditorSnippet {
+
+    /// Applies this snippet to `textView` at its current insertion point,
+    /// updating the text and cursor, then notifying the text view's delegate
+    /// (UITextView does not report programmatic edits on its own).
+    @MainActor
+    public func apply(to textView: UITextView) {
+      let text = textView.text ?? ""
+      let result = apply(
+        to: text, cursor: Self.characterOffset(of: textView.selectedRange, in: text))
+
+      // Replacing `text` wholesale resets the scroll to the top, so preserve
+      // and restore the content offset around the edit.
+      let savedOffset = textView.contentOffset
+      textView.text = result.text
+      textView.layoutIfNeeded()
+      textView.selectedRange = Self.range(forCharacterOffset: result.cursor, in: result.text)
+      textView.setContentOffset(savedOffset, animated: false)
+      textView.delegate?.textViewDidChange?(textView)
+    }
+
+    /// The character (grapheme) offset of a UTF-16 `NSRange`'s start.
+    private static func characterOffset(of nsRange: NSRange, in text: String) -> Int {
+      guard let range = Range(nsRange, in: text) else { return text.count }
+      return text.distance(from: text.startIndex, to: range.lowerBound)
+    }
+
+    /// A zero-length UTF-16 `NSRange` at the given character offset.
+    private static func range(forCharacterOffset offset: Int, in text: String) -> NSRange {
+      let clamped = min(max(offset, 0), text.count)
+      let index = text.index(text.startIndex, offsetBy: clamped)
+      return NSRange(index..<index, in: text)
+    }
+  }
+
+  // MARK: - Input-accessory toolbar
+
+  /// A keyboard input-accessory toolbar with one button per ``EditorSnippet``,
+  /// wired to a `UITextView`. Drop it onto any UIKit text editor:
+  ///
+  /// ```swift
+  /// textView.inputAccessoryView = NorgKeyboardAccessory(textView: textView)
+  /// // or:
+  /// textView.installNorgKeyboardAccessory()
+  /// ```
+  ///
+  /// The toolbar holds the text view weakly, so it does not retain it.
+  public final class NorgKeyboardAccessory: UIToolbar {
+
+    private weak var textView: UITextView?
+
+    public init(textView: UITextView) {
+      self.textView = textView
+      super.init(frame: CGRect(x: 0, y: 0, width: 0, height: 50))
+      autoresizingMask = .flexibleWidth
+      buildItems()
+    }
+
+    @available(*, unavailable)
+    required init?(coder: NSCoder) {
+      fatalError("init(coder:) is not supported")
+    }
+
+    /// Fixed glyph size so the icons stay consistent regardless of the
+    /// toolbar's height (a taller bar would otherwise scale them up).
+    private static let symbolConfiguration = UIImage.SymbolConfiguration(
+      pointSize: 17, weight: .regular)
+
+    private func buildItems() {
+      let buttons = EditorSnippet.allCases.map { snippet -> UIBarButtonItem in
+        let image = UIImage(
+          systemName: snippet.systemImage, withConfiguration: Self.symbolConfiguration)
+        let action = UIAction(image: image) { [weak self] _ in
+          guard let textView = self?.textView else { return }
+          snippet.apply(to: textView)
+        }
+        let item = UIBarButtonItem(primaryAction: action)
+        item.accessibilityLabel = snippet.label
+        return item
+      }
+      // Center the group of buttons with flexible space on both sides.
+      setItems([.flexibleSpace()] + buttons + [.flexibleSpace()], animated: false)
+    }
+  }
+
+  extension UITextView {
+
+    /// Installs a ``NorgKeyboardAccessory`` as this text view's input accessory.
+    public func installNorgKeyboardAccessory() {
+      inputAccessoryView = NorgKeyboardAccessory(textView: self)
+    }
+  }
+#endif