View .onHover { Bool in } modifier

[MiaKoring]

This PR introduces a new .onHover modifier to Views.
Related Issue: #211
Added in this PR:

• Extension View

  • onHover { Bool in }

• protocol AppBackend

  • createHoverTarget
  • updateHoverTarget
  • Default implementation for Backends without implementation

• Backend Support

  • AppKitBackend
  • UIKitBackend
  • GtkBackend
  • WinUIBackend

• Other changes:

  • left & right NSClickGestureRecognizer now get set to nil in NSCustomTapGestureTarget when corresponding function gets set to nil
  • UISlider now Supports macCatalyst (added through compilerflag)
  • Added HoverExample
  • (format_and_lint.sh and generate.sh automatic changes)

HoverExample erfolgreich getestet auf:
macOS 26 (AppKitBackend, GtkBackend, UIKitBackend (macCatalyst))
iPadOS 26 (UIKitBackend)
Windows 11 (WinUI Backend)
Fedora 44 (GtkBackend)

Notes:
Gtk versions below 4.20.0 may encounter compiling problems. I don’t know why or what caused it, I only used the generate script, but on 4.18.6 on Fedora 42 I got this Error:

/home/mia/Documents/swift-cross-ui/Sources/Gtk/Generated/PadActionType.swift:28:6: error: cannot find 'GTK_PAD_ACTION_DIAL' in scope
26 | case GTK_PAD_ACTION_STRIP:
27 |     self = .strip
28 | case GTK_PAD_ACTION_DIAL:
   |      `- error: cannot find 'GTK_PAD_ACTION_DIAL' in scope
29 |     self = .dial
30 |             default:

I checked and it should’ve been available since 4.0 https://docs.gtk.org/gtk4/enum.PadActionType.html
Maybe someone knows how to fix it and maybe it was just a local issue.

test.sh output

   Test Suite 'All tests' started at 2025-09-08 00:03:46.577.
Test Suite 'swift-cross-uiPackageTests.xctest' started at 2025-09-08 00:03:46.584.
Test Suite 'SwiftCrossUITests' started at 2025-09-08 00:03:46.584.
Test Case '-[SwiftCrossUITests.SwiftCrossUITests testBasicLayout]' started.
/Users/miakoring/Documents/Fork/swift-cross-ui/Tests/SwiftCrossUITests/SwiftCrossUITests.swift:203: error: -[SwiftCrossUITests.SwiftCrossUITests testBasicLayout] : XCTAssertEqual failed: ("ViewSize(size: SIMD2<Int>(102, 104), idealSize: SIMD2<Int>(102, 104), idealWidthForProposedHeight: 102, idealHeightForProposedWidth: 104, minimumWidth: 102, minimumHeight: 104, maximumWidth: 102.0, maximumHeight: 104.0, participateInStackLayoutsWhenEmpty: true)") is not equal to ("ViewSize(size: SIMD2<Int>(92, 96), idealSize: SIMD2<Int>(92, 96), idealWidthForProposedHeight: 92, idealHeightForProposedWidth: 96, minimumWidth: 92, minimumHeight: 96, maximumWidth: 92.0, maximumHeight: 96.0, participateInStackLayoutsWhenEmpty: true)") - View update result mismatch
Test Case '-[SwiftCrossUITests.SwiftCrossUITests testBasicLayout]' failed (0.204 seconds).
Test Case '-[SwiftCrossUITests.SwiftCrossUITests testCodableNavigationPath]' started.
Test Case '-[SwiftCrossUITests.SwiftCrossUITests testCodableNavigationPath]' passed (0.001 seconds).
Test Case '-[SwiftCrossUITests.SwiftCrossUITests testStateObservation]' started.
Test Case '-[SwiftCrossUITests.SwiftCrossUITests testStateObservation]' passed (0.000 seconds).
Test Case '-[SwiftCrossUITests.SwiftCrossUITests testThrottledStateObservation]' started.
Test Case '-[SwiftCrossUITests.SwiftCrossUITests testThrottledStateObservation]' passed (0.225 seconds).
Test Suite 'SwiftCrossUITests' failed at 2025-09-08 00:03:47.014.
	 Executed 4 tests, with 1 failure (0 unexpected) in 0.430 (0.431) seconds
Test Suite 'swift-cross-uiPackageTests.xctest' failed at 2025-09-08 00:03:47.014.
	 Executed 4 tests, with 1 failure (0 unexpected) in 0.430 (0.431) seconds
Test Suite 'All tests' failed at 2025-09-08 00:03:47.014.
	 Executed 4 tests, with 1 failure (0 unexpected) in 0.430 (0.437) seconds
􀟈  Test run started.
􀄵  Testing Library Version: 1084
􀄵  Target Platform: arm64e-apple-macos14.0
􁁛  Test run with 0 tests in 0 suites passed after 0.001 seconds.