fix: stabilize native iOS share handoff

Docs/Integration.md

@@ -33,6 +33,19 @@ disable Meta automatic initialization and call
 `NativeFacebookShare.ConfigureAndInitialize(app.Handle, trackingAllowed)` only
 after the ATT decision, immediately before the first share. Then call
 `NativeFacebookShare.SharePhotoAsync(...)`; no caption is accepted.
+Forward Facebook callback URLs to
+`NativeFacebookShare.HandleOpenUrl(app.Handle, url.Handle, options.Handle)`.
+Share-only host applications should filter by their configured Facebook URL
+scheme before invoking this handler.
+
+The photo wrapper uses ShareKit's native-app dialog mode. A share operation
+completes its managed callback at most once, including when ShareKit reports a
+synchronous presentation failure followed by a late delegate callback.
+
+When Facebook returns to the host app, the wrapper clears only Meta's private
+bridge marker from the general pasteboard, and does so without reading the
+pasteboard. This avoids triggering an iOS paste-authorization prompt while
+leaving unrelated pasteboard content untouched.
 
 ## 3) Feature selection
 

src/Kapusch.FacebookApisForiOSComponents/Facebook/NativeFacebookShare.iOS.cs

@@ -3,7 +3,7 @@
 
 namespace Kapusch.Facebook.iOS;
 
-public static unsafe class NativeFacebookShare
+public static unsafe partial class NativeFacebookShare
 {
 	public static void ConfigureAndInitialize(
 		IntPtr uiApplicationHandle,
@@ -13,7 +13,27 @@ bool trackingAllowed
 		if (uiApplicationHandle == IntPtr.Zero)
 			throw new ArgumentException("UIApplication is required.");
 
-		ResolveConfigureAndInitialize()(uiApplicationHandle, trackingAllowed ? (byte)1 : (byte)0);
+		ConfigureAndInitializeNative(
+			uiApplicationHandle,
+			trackingAllowed ? (byte)1 : (byte)0
+		);
+	}
+
+	public static bool HandleOpenUrl(
+		IntPtr uiApplicationHandle,
+		IntPtr nsUrlHandle,
+		IntPtr optionsHandle
+	)
+	{
+		if (uiApplicationHandle == IntPtr.Zero || nsUrlHandle == IntPtr.Zero)
+			return false;
+
+		return HandleOpenUrlNative(
+				uiApplicationHandle,
+				nsUrlHandle,
+				optionsHandle
+			)
+			!= 0;
 	}
 
 	public static Task<NativeFacebookShareResult> SharePhotoAsync(
@@ -36,7 +56,7 @@ public static Task<NativeFacebookShareResult> SharePhotoAsync(
 		var imagePathPointer = Marshal.StringToCoTaskMemUTF8(imagePath);
 		try
 		{
-			ResolveSharePhoto()(
+			SharePhotoNative(
 				presentingViewControllerHandle,
 				imagePathPointer,
 				&ShareCallback,
@@ -75,24 +95,27 @@ private static void ShareCallback(int status, IntPtr errorCode, IntPtr context)
 		}
 	}
 
-	private static IntPtr Resolve(string symbol) =>
-		NativeLibrary.GetExport(NativeLibrary.GetMainProgramHandle(), symbol);
+	[LibraryImport(
+		"__Internal",
+		EntryPoint = "kfb_facebook_share_configure_and_initialize"
+	)]
+	private static partial void ConfigureAndInitializeNative(
+		IntPtr uiApplicationHandle,
+		byte trackingAllowed
+	);
 
-	private static delegate* unmanaged[Cdecl]<IntPtr, byte, void> ResolveConfigureAndInitialize() =>
-		(delegate* unmanaged[Cdecl]<IntPtr, byte, void>)Resolve(
-			"kfb_facebook_share_configure_and_initialize"
-		);
+	[LibraryImport("__Internal", EntryPoint = "kfb_facebook_share_handle_open_url")]
+	private static partial byte HandleOpenUrlNative(
+		IntPtr uiApplicationHandle,
+		IntPtr nsUrlHandle,
+		IntPtr optionsHandle
+	);
 
-	private static delegate* unmanaged[Cdecl]<
-		IntPtr,
-		IntPtr,
-		delegate* unmanaged[Cdecl]<int, IntPtr, IntPtr, void>,
-		IntPtr,
-		void> ResolveSharePhoto() =>
-		(delegate* unmanaged[Cdecl]<
-			IntPtr,
-			IntPtr,
-			delegate* unmanaged[Cdecl]<int, IntPtr, IntPtr, void>,
-			IntPtr,
-			void>)Resolve("kfb_facebook_share_photo");
+	[LibraryImport("__Internal", EntryPoint = "kfb_facebook_share_photo")]
+	private static partial void SharePhotoNative(
+		IntPtr presentingViewControllerHandle,
+		IntPtr imagePath,
+		delegate* unmanaged[Cdecl]<int, IntPtr, IntPtr, void> callback,
+		IntPtr context
+	);
 }

src/Kapusch.FacebookApisForiOSComponents/Native/iOS/KapuschFacebookAuthInterop/Sources/KapuschFacebookShareInterop/Interop.swift

@@ -1,9 +1,24 @@
 import Foundation
+import OSLog
 import UIKit
 
 import FacebookCore
 import FacebookShare
 
+private let shareLogger = Logger(
+	subsystem: Bundle.main.bundleIdentifier ?? "Kapusch.Facebook.iOS",
+	category: "FacebookShare"
+)
+
+private enum FacebookBridgePasteboard {
+	static let dataType = "com.facebook.Facebook.FBAppBridgeType"
+
+	static func clearPendingShareDataWithoutReading() {
+		UIPasteboard.general.setData(Data(), forPasteboardType: dataType)
+		shareLogger.debug("Cleared pending Facebook bridge data without reading the pasteboard.")
+	}
+}
+
 public typealias KapuschFacebookShareCallback = @convention(c) (
 	Int32,
 	UnsafePointer<CChar>?,
@@ -32,19 +47,28 @@ private func invokeShareCallback(
 private final class ShareDelegate: NSObject, SharingDelegate {
 	let callback: KapuschFacebookShareCallback
 	let context: UnsafeMutableRawPointer
+	private(set) var didFinish = false
 
 	init(callback: @escaping KapuschFacebookShareCallback, context: UnsafeMutableRawPointer) {
 		self.callback = callback
 		self.context = context
 	}
 
 	func sharer(_ sharer: Sharing, didCompleteWithResults results: [String: Any]) {
+		guard !didFinish else { return }
+		didFinish = true
+		shareLogger.info("Facebook share completed.")
 		invokeShareCallback(callback, status: .success, context: context)
 		ShareState.clear()
 	}
 
 	func sharer(_ sharer: Sharing, didFailWithError error: Error) {
+		guard !didFinish else { return }
+		didFinish = true
 		let nsError = error as NSError
+		shareLogger.error(
+			"Facebook share failed. domain=\(nsError.domain, privacy: .public) code=\(nsError.code)"
+		)
 		invokeShareCallback(
 			callback,
 			status: .failed,
@@ -55,6 +79,9 @@ private final class ShareDelegate: NSObject, SharingDelegate {
 	}
 
 	func sharerDidCancel(_ sharer: Sharing) {
+		guard !didFinish else { return }
+		didFinish = true
+		shareLogger.info("Facebook share cancelled.")
 		invokeShareCallback(callback, status: .cancelled, context: context)
 		ShareState.clear()
 	}
@@ -76,6 +103,9 @@ public func kfb_facebook_share_configure_and_initialize(
 	_ applicationPtr: UnsafeMutableRawPointer,
 	_ trackingAllowed: Bool
 ) {
+	shareLogger.debug(
+		"Configuring Facebook Share SDK. trackingAllowed=\(trackingAllowed, privacy: .public)"
+	)
 	Settings.shared.isAutoLogAppEventsEnabled = false
 	Settings.shared.isAdvertiserIDCollectionEnabled = trackingAllowed
 	Settings.shared.isAdvertiserTrackingEnabled = trackingAllowed
@@ -100,7 +130,9 @@ public func kfb_facebook_share_photo(
 	_ callback: @escaping KapuschFacebookShareCallback,
 	_ context: UnsafeMutableRawPointer
 ) {
+	shareLogger.debug("Facebook photo share requested.")
 	guard ShareState.dialog == nil else {
+		shareLogger.error("Facebook share rejected because another request is in progress.")
 		invokeShareCallback(
 			callback,
 			status: .failed,
@@ -112,6 +144,7 @@ public func kfb_facebook_share_photo(
 
 	let imagePath = String(cString: imagePathPtr)
 	guard let image = UIImage(contentsOfFile: imagePath) else {
+		shareLogger.error("Facebook share could not decode the image.")
 		invokeShareCallback(
 			callback,
 			status: .failed,
@@ -133,9 +166,14 @@ public func kfb_facebook_share_photo(
 		content: content,
 		delegate: delegate
 	)
+	dialog.mode = .native
 	ShareState.delegate = delegate
 	ShareState.dialog = dialog
-	if !dialog.show() {
+	shareLogger.debug("Facebook ShareDialog canShow=\(dialog.canShow, privacy: .public)")
+	let shown = dialog.show()
+	shareLogger.debug("Facebook ShareDialog show returned \(shown, privacy: .public)")
+	if !shown && !delegate.didFinish {
+		shareLogger.error("Facebook ShareDialog was unavailable without a delegate error.")
 		ShareState.clear()
 		invokeShareCallback(
 			callback,
@@ -145,3 +183,35 @@ public func kfb_facebook_share_photo(
 		)
 	}
 }
+
+@_cdecl("kfb_facebook_share_handle_open_url")
+public func kfb_facebook_share_handle_open_url(
+	_ applicationPtr: UnsafeMutableRawPointer,
+	_ urlPtr: UnsafeMutableRawPointer,
+	_ optionsPtr: UnsafeMutableRawPointer?
+) -> Bool {
+	let application = Unmanaged<UIApplication>
+		.fromOpaque(applicationPtr)
+		.takeUnretainedValue()
+	let url = Unmanaged<NSURL>.fromOpaque(urlPtr).takeUnretainedValue() as URL
+	guard let appID = Bundle.main.infoDictionary?["FacebookAppID"] as? String,
+		url.scheme?.caseInsensitiveCompare("fb\(appID)") == .orderedSame
+	else {
+		return false
+	}
+	let options: NSDictionary? = {
+		guard let optionsPtr else { return nil }
+		return Unmanaged<NSDictionary>.fromOpaque(optionsPtr).takeUnretainedValue()
+	}()
+	let openUrlOptions = options as? [UIApplication.OpenURLOptionsKey: Any] ?? [:]
+
+	if ShareState.dialog != nil {
+		FacebookBridgePasteboard.clearPendingShareDataWithoutReading()
+	}
+
+	return ApplicationDelegate.shared.application(
+		application,
+		open: url,
+		options: openUrlOptions
+	)
+}

src/Kapusch.FacebookApisForiOSComponents/nuget-readme.md

@@ -6,5 +6,8 @@ This package provides:
 
 Set `KapuschFacebookFeatures` to `Login` (default), `Share`, or `Login;Share`.
 SDK 18.0.2 requires FBAEMKit whenever ShareKit/CoreKit is selected.
+Photo sharing uses ShareKit's native-app dialog, guarantees one managed
+completion per request, and avoids reading the general pasteboard when cleaning
+Meta's app-bridge marker on return.
 
 See the repo `README.md` and `Docs/Integration.md` for integration steps.

tests/validate-feature-selection.sh

@@ -3,6 +3,45 @@
 set -euo pipefail
 
 project="tests/FeatureSelection.proj"
+share_source="src/Kapusch.FacebookApisForiOSComponents/Facebook/NativeFacebookShare.iOS.cs"
+share_interop_source="src/Kapusch.FacebookApisForiOSComponents/Native/iOS/KapuschFacebookAuthInterop/Sources/KapuschFacebookShareInterop/Interop.swift"
+
+contains_fixed_text() {
+	local pattern="$1"
+	local file="$2"
+
+	if command -v rg >/dev/null 2>&1; then
+		rg -F "$pattern" "$file" >/dev/null
+	else
+		grep -Fq -- "$pattern" "$file"
+	fi
+}
+
+if contains_fixed_text "NativeLibrary.GetExport" "$share_source"; then
+	echo "Facebook Share must use static __Internal imports so iOS retains its native symbols." >&2
+	exit 1
+fi
+
+for symbol in \
+	kfb_facebook_share_configure_and_initialize \
+	kfb_facebook_share_handle_open_url \
+	kfb_facebook_share_photo; do
+	contains_fixed_text "EntryPoint = \"$symbol\"" "$share_source" \
+		|| { echo "Missing static Facebook Share import: $symbol" >&2; exit 1; }
+done
+
+contains_fixed_text "guard !didFinish else { return }" "$share_interop_source" \
+	|| { echo "Facebook Share callbacks must be idempotent." >&2; exit 1; }
+contains_fixed_text "if !shown && !delegate.didFinish" "$share_interop_source" \
+	|| { echo "Facebook Share must not invoke a second callback after ShareKit reports a synchronous failure." >&2; exit 1; }
+contains_fixed_text "dialog.mode = .native" "$share_interop_source" \
+	|| { echo "Facebook photo share must use the native Facebook dialog instead of the deprecated iOS share sheet." >&2; exit 1; }
+contains_fixed_text "FacebookBridgePasteboard.clearPendingShareDataWithoutReading()" "$share_interop_source" \
+	|| { echo "Facebook native share callbacks must clear bridge data without triggering an iOS paste read." >&2; exit 1; }
+if contains_fixed_text "data(forPasteboardType:" "$share_interop_source"; then
+	echo "Facebook Share wrapper must never read the general pasteboard." >&2
+	exit 1
+fi
 
 dotnet msbuild "$project" -t:ValidateFeatureSelection -p:ExpectedLoginEnabled=True -p:ExpectedShareEnabled=False