Build UIKitBackend in CI (#119)

* Build UIKitBackend in CI

* Fix workflow name

* Use matrix instead of for loop

* Fix tvOS build by disabling keyboard toolbar

* Respell available clause and link to forums

Author: bbrk24

.github/workflows/swift-uikit.yml

@@ -0,0 +1,61 @@
+name: Build UIKitBackend
+
+on:
+  push:
+    branches-ignore:
+      - 'gh-pages'
+  pull_request:
+    branches-ignore:
+      - 'gh-pages'
+
+jobs:
+  build-uikit:
+    runs-on: macos-14
+    strategy:
+      matrix:
+        devicetype:
+          - iPhone
+          - iPad
+          - TV
+    steps:
+    - name: Force Xcode 15.4
+      run: sudo xcode-select -switch /Applications/Xcode_15.4.app
+    - uses: actions/checkout@v3
+    - name: Build
+      run: |
+        set -uo pipefail
+        devicetype=${{ matrix.devicetype }}
+        set +e
+        deviceid=$(xcrun simctl list devices $devicetype available | grep -v -- -- | tail -n 1 | grep -oE '[0-9A-F\-]{36}')
+        if [ $? -eq 0 ]; then
+          set -e
+          (
+            buildtarget () {
+              xcodebuild -scheme "$1" -destination "id=$deviceid" build
+            }
+
+            buildtarget SwiftCrossUI
+            buildtarget UIKitBackend
+
+            cd Examples
+
+            buildtarget CounterExample
+            buildtarget GreetingGeneratorExample
+            buildtarget NavigationExample
+            buildtarget StressTestExample
+            buildtarget NotesExample
+
+            if [ $devicetype != TV ]; then
+              # Slider is not implemented for tvOS
+              buildtarget ControlsExample
+              buildtarget RandomNumberGeneratorExample
+            fi
+
+            if [ $devicetype = iPad ]; then
+              # NavigationSplitView is only implemented for iPad
+              buildtarget SplitExample
+            fi
+          )
+        else
+          echo "No $devicetype simulators found" >&2
+        fi

Sources/UIKitBackend/KeyboardToolbar.swift

@@ -8,6 +8,7 @@ import UIKit
 /// items will not cause the toolbar to be updated. The toolbar is only updated when the view
 /// containing the ``View/keyboardToolbar(animateChanges:body:)`` modifier is updated, so any
 /// state necessary for the toolbar should live in the view itself.
+@available(tvOS, unavailable)
 public protocol ToolbarItem {
     /// The type of bar button item used to represent this item in UIKit.
     associatedtype ItemType: UIBarButtonItem
@@ -19,6 +20,7 @@ public protocol ToolbarItem {
     func updateBarButtonItem(_ item: inout ItemType)
 }
 
+@available(tvOS, unavailable)
 @resultBuilder
 public enum ToolbarBuilder {
     public enum Component {
@@ -56,6 +58,7 @@ public enum ToolbarBuilder {
     }
 }
 
+@available(tvOS, unavailable)
 extension Button: ToolbarItem {
     public final class ItemType: UIBarButtonItem {
         var callback: () -> Void
@@ -90,7 +93,11 @@ extension Button: ToolbarItem {
     }
 }
 
-@available(iOS 14, macCatalyst 14, tvOS 14, *)
+// Despite the fact that this is unavailable on tvOS, the `introduced: 14`
+// clause is required for all current Swift versions to accept it.
+// See https://forums.swift.org/t/contradictory-available-s-are-required/78831
+@available(iOS 14, macCatalyst 14, *)
+@available(tvOS, unavailable, introduced: 14)
 extension Spacer: ToolbarItem {
     public func createBarButtonItem() -> UIBarButtonItem {
         if let minLength, minLength > 0 {
@@ -110,6 +117,7 @@ extension Spacer: ToolbarItem {
     }
 }
 
+@available(tvOS, unavailable)
 struct FixedWidthToolbarItem<Base: ToolbarItem>: ToolbarItem {
     var base: Base
     var width: Int?
@@ -131,7 +139,8 @@ struct FixedWidthToolbarItem<Base: ToolbarItem>: ToolbarItem {
 }
 
 // Setting width on a flexible space is ignored, you must use a fixed space from the outset
-@available(iOS 14, macCatalyst 14, tvOS 14, *)
+@available(iOS 14, macCatalyst 14, *)
+@available(tvOS, unavailable, introduced: 14)
 struct FixedWidthSpacerItem: ToolbarItem {
     var width: Int?
 
@@ -148,6 +157,7 @@ struct FixedWidthSpacerItem: ToolbarItem {
     }
 }
 
+@available(tvOS, unavailable)
 struct ColoredToolbarItem<Base: ToolbarItem>: ToolbarItem {
     var base: Base
     var color: Color
@@ -164,13 +174,14 @@ struct ColoredToolbarItem<Base: ToolbarItem>: ToolbarItem {
     }
 }
 
+@available(tvOS, unavailable)
 extension ToolbarItem {
     /// A toolbar item with the specified width.
     ///
     /// If `width` is positive, the item will have that exact width. If `width` is zero or
     /// nil, the item will have its natural size.
     public func frame(width: Int?) -> any ToolbarItem {
-        if #available(iOS 14, macCatalyst 14, tvOS 14, *),
+        if #available(iOS 14, macCatalyst 14, *),
             self is Spacer || self is FixedWidthSpacerItem
         {
             FixedWidthSpacerItem(width: width)
@@ -185,6 +196,7 @@ extension ToolbarItem {
     }
 }
 
+@available(tvOS, unavailable)
 indirect enum ToolbarItemLocation: Hashable {
     case expression(inside: ToolbarItemLocation?)
     case block(index: Int, inside: ToolbarItemLocation?)
@@ -194,6 +206,7 @@ indirect enum ToolbarItemLocation: Hashable {
     case eitherSecond(inside: ToolbarItemLocation?)
 }
 
+@available(tvOS, unavailable)
 final class KeyboardToolbar: UIToolbar {
     var locations: [ToolbarItemLocation: UIBarButtonItem] = [:]
 
@@ -205,7 +218,7 @@ final class KeyboardToolbar: UIToolbar {
         var newLocations: [ToolbarItemLocation: UIBarButtonItem] = [:]
 
         visitItems(component: components, inside: nil) { location, expression in
-            var item =
+            let item =
                 if let oldItem = locations[location] {
                     updateErasedItem(expression, oldItem)
                 } else {
@@ -270,10 +283,12 @@ final class KeyboardToolbar: UIToolbar {
     }
 }
 
+@available(tvOS, unavailable)
 enum ToolbarKey: EnvironmentKey {
     static let defaultValue: ((KeyboardToolbar) -> Void)? = nil
 }
 
+@available(tvOS, unavailable)
 extension EnvironmentValues {
     var updateToolbar: ((KeyboardToolbar) -> Void)? {
         get { self[ToolbarKey.self] }
@@ -287,6 +302,7 @@ extension View {
     ///   - animateChanges: Whether to animate updates when an item is added, removed, or
     ///     updated
     ///   - body: The toolbar's contents
+    @available(tvOS, unavailable)
     public func keyboardToolbar(
         animateChanges: Bool = true,
         @ToolbarBuilder body: @escaping () -> ToolbarBuilder.FinalResult

Sources/UIKitBackend/UIKitBackend+Control.swift

@@ -241,14 +241,17 @@ extension UIKitBackend {
         textFieldWidget.onChange = onChange
         textFieldWidget.onSubmit = onSubmit
 
-        if let updateToolbar = environment.updateToolbar {
-            let toolbar =
-                (textFieldWidget.child.inputAccessoryView as? KeyboardToolbar) ?? KeyboardToolbar()
-            updateToolbar(toolbar)
-            textFieldWidget.child.inputAccessoryView = toolbar
-        } else {
-            textFieldWidget.child.inputAccessoryView = nil
-        }
+        #if os(iOS)
+            if let updateToolbar = environment.updateToolbar {
+                let toolbar =
+                    (textFieldWidget.child.inputAccessoryView as? KeyboardToolbar)
+                    ?? KeyboardToolbar()
+                updateToolbar(toolbar)
+                textFieldWidget.child.inputAccessoryView = toolbar
+            } else {
+                textFieldWidget.child.inputAccessoryView = nil
+            }
+        #endif
     }
 
     public func setContent(ofTextField textField: Widget, to content: String) {