[ios]use DefaultLauncher to fix compile error when conforming UIApplication to Launcher due to main actor annotation

bump version

Author: hellohuanlin

packages/url_launcher/url_launcher_ios/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 6.3.1
+
+* Fixes a compile error when comforming UIApplication to Launcher in iOS 18 Beta 3.
+
 ## 6.3.0
 
 * Adds Swift Package Manager compatibility.

packages/url_launcher/url_launcher_ios/ios/url_launcher_ios/Sources/url_launcher_ios/Launcher.swift

@@ -18,5 +18,21 @@ protocol Launcher {
     completionHandler completion: ((Bool) -> Void)?)
 }
 
-/// Launcher is intentionally a direct passthroguh to UIApplication.
-extension UIApplication: Launcher {}
+// TODO(hellohuanlin): This wrapper is a workaround for iOS 18 Beta 3 where completionHandler is annotated with @MainActor @Sendable, resulting in compile error when conforming UIApplication to Launcher. We should try again in newer betas.
+/// A default URL launcher.
+final class DefaultLauncher: Launcher {
+  func canOpenURL(_ url: URL) -> Bool {
+    return UIApplication.shared.canOpenURL(url)
+  }
+  
+  func open(
+    _ url: URL,
+    options: [UIApplication.OpenExternalURLOptionsKey: Any],
+    completionHandler completion: ((Bool) -> Void)?)
+  {
+    UIApplication.shared.open(
+      url,
+      options: options,
+      completionHandler: completion)
+  }
+}

packages/url_launcher/url_launcher_ios/ios/url_launcher_ios/Sources/url_launcher_ios/URLLauncherPlugin.swift

@@ -22,7 +22,7 @@ public final class URLLauncherPlugin: NSObject, FlutterPlugin, UrlLauncherApi {
     UIApplication.shared.keyWindow?.rootViewController?.topViewController
   }
 
-  init(launcher: Launcher = UIApplication.shared) {
+  init(launcher: Launcher = DefaultLauncher()) {
     self.launcher = launcher
   }
 

packages/url_launcher/url_launcher_ios/pubspec.yaml

@@ -2,7 +2,7 @@ name: url_launcher_ios
 description: iOS implementation of the url_launcher plugin.
 repository: https://github.com/flutter/packages/tree/main/packages/url_launcher/url_launcher_ios
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+url_launcher%22
-version: 6.3.0
+version: 6.3.1
 
 environment:
   sdk: ^3.2.3