Properly callback URL launch results for iOS

flutter_custom_tabs/README.md

@@ -76,7 +76,7 @@ void _launchURL(BuildContext context) async {
       ),
     );
   } catch (e) {
-    // An exception is thrown if browser app is not installed on Android device.
+    // If the URL launch fails, an exception will be thrown. (For example, if no browser app is installed on the Android device.)
     debugPrint(e.toString());
   }
 }

flutter_custom_tabs/lib/src/launcher.dart

@@ -38,7 +38,7 @@ import 'package:flutter_custom_tabs_platform_interface/flutter_custom_tabs_platf
 ///     ),
 ///   );
 /// } catch (e) {
-///   // An exception is thrown if browser app is not installed on Android device.
+///   // If the URL launch fails, an exception will be thrown. (For example, if no browser app is installed on the Android device.)
 /// }
 /// ```
 ///

flutter_custom_tabs/lib/src/launcher_lite.dart

@@ -22,7 +22,7 @@ import 'types/launch_options.dart';
 ///     ),
 ///   );
 /// } catch (e) {
-///   // An exception is thrown if browser app is not installed on Android device.
+///   // If the URL launch fails, an exception will be thrown. (For example, if no browser app is installed on the Android device.)
 /// }
 @experimental
 Future<void> launchUrl(

flutter_custom_tabs_android/android/src/main/java/com/github/droibit/flutter/plugins/customtabs/CustomTabsLauncher.java

@@ -28,7 +28,8 @@
 import static java.util.Objects.requireNonNull;
 
 class CustomTabsLauncher implements Messages.CustomTabsApi {
-    private static final String CODE_LAUNCH_ERROR = "LAUNCH_ERROR";
+    @VisibleForTesting
+    static final String CODE_LAUNCH_ERROR = "LAUNCH_ERROR";
     private static final int REQUEST_CODE_CUSTOM_TABS = 0;
 
     private final @NonNull CustomTabsFactory customTabsFactory;

flutter_custom_tabs_android/android/src/test/java/com/github/droibit/flutter/plugins/customtabs/CustomTabsLauncherTest.java

@@ -59,6 +59,9 @@ public void launchWithoutActivity() {
             fail("error");
         } catch (Exception e) {
             assertThat(e).isInstanceOf(FlutterError.class);
+
+            final FlutterError actualError = ((FlutterError) e);
+            assertThat(actualError.code).isEqualTo(CustomTabsLauncher.CODE_LAUNCH_ERROR);
         }
     }
 
@@ -122,6 +125,9 @@ public void launchExternalBrowserFailure() {
             fail("error");
         } catch (Exception e) {
             assertThat(e).isInstanceOf(FlutterError.class);
+
+            final FlutterError actualError = ((FlutterError) e);
+            assertThat(actualError.code).isEqualTo(CustomTabsLauncher.CODE_LAUNCH_ERROR);
         }
     }
 
@@ -198,6 +204,9 @@ public void launchCustomTabsFailure() {
             fail("error");
         } catch (Exception e) {
             assertThat(e).isInstanceOf(FlutterError.class);
+
+            final FlutterError actualError = ((FlutterError) e);
+            assertThat(actualError.code).isEqualTo(CustomTabsLauncher.CODE_LAUNCH_ERROR);
         }
     }
 }

flutter_custom_tabs_ios/example/ios/RunnerTests/CustomTabsPluginTest.swift

@@ -19,6 +19,8 @@ final class CustomTabsPluginTest: XCTestCase {
     }
 
     func testPresentSFSafariViewController() {
+        launcher.setPresentCompletionHandlerResults(true)
+
         let url = URL(string: "https://example.com")!
         let options = SFSafariViewControllerOptions()
         plugin.launchURL(url.absoluteString, prefersDeepLink: false, options: options) { result in
@@ -33,6 +35,27 @@ final class CustomTabsPluginTest: XCTestCase {
         XCTAssertTrue(actualArgment.viewControllerToPresent is SFSafariViewController)
     }
 
+    func testFailedToPresentSFSafariViewController() {
+        launcher.setPresentCompletionHandlerResults(false)
+
+        let url = URL(string: "https://example.com")!
+        let options = SFSafariViewControllerOptions()
+        plugin.launchURL(url.absoluteString, prefersDeepLink: false, options: options) { result in
+            if case let .failure(error) = result {
+                XCTAssertTrue(error is FlutterError)
+                let actualError = error as! FlutterError
+                XCTAssertEqual(actualError.code, FlutterError.erorCode)
+            } else {
+                XCTFail("error")
+            }
+        }
+        XCTAssertTrue(launcher.openArgumentStack.isEmpty)
+        XCTAssertEqual(launcher.presentArgumentStack.count, 1)
+
+        let actualArgment = launcher.presentArgumentStack.first!
+        XCTAssertTrue(actualArgment.viewControllerToPresent is SFSafariViewController)
+    }
+
     func testOpenExternalBrowser() throws {
         launcher.setOpenCompletionHandlerResults(true)
 
@@ -47,6 +70,24 @@ final class CustomTabsPluginTest: XCTestCase {
         ])
     }
 
+    func testFailedToOpenExternalBrowser() throws {
+        launcher.setOpenCompletionHandlerResults(false)
+
+        let url = URL(string: "https://example.com")!
+        plugin.launchURL(url.absoluteString, prefersDeepLink: false, options: nil) { result in
+            if case let .failure(error) = result {
+                XCTAssertTrue(error is FlutterError)
+                let actualError = error as! FlutterError
+                XCTAssertEqual(actualError.code, FlutterError.erorCode)
+            } else {
+                XCTFail("error")
+            }
+        }
+        XCTAssertEqual(launcher.openArgumentStack, [
+            .init(url: url, options: [:]),
+        ])
+    }
+
     // MARK: - Deep Linking
 
     func testDeepLinkToNativeApp() throws {
@@ -82,6 +123,7 @@ final class CustomTabsPluginTest: XCTestCase {
 
     func testFallBackToSFSfariViewController() throws {
         launcher.setOpenCompletionHandlerResults(false)
+        launcher.setPresentCompletionHandlerResults(true)
 
         let url = URL(string: "https://example.com")!
         let options = SFSafariViewControllerOptions()

flutter_custom_tabs_ios/example/ios/RunnerTests/MockLauncher.swift

@@ -4,6 +4,7 @@ import Foundation
 
 class MockLauncher: Launcher {
     private var openCompletionHandlerResults = [Bool]()
+    private var presentCompletionHandlerResults = [Bool]()
     private(set) var openArgumentStack = [OpenArgument]()
     private(set) var presentArgumentStack = [PresentArgument]()
 
@@ -13,6 +14,10 @@ class MockLauncher: Launcher {
         openCompletionHandlerResults.append(contentsOf: values)
     }
 
+    func setPresentCompletionHandlerResults(_ values: Bool...) {
+        presentCompletionHandlerResults.append(contentsOf: values)
+    }
+
     override func open(
         _ url: URL,
         options: [UIApplication.OpenExternalURLOptionsKey: Any] = [:],
@@ -24,11 +29,13 @@ class MockLauncher: Launcher {
         completion?(opened)
     }
 
-    override func present(_ viewControllerToPresent: UIViewController, completion: (() -> Void)? = nil) {
+    override func present(_ viewControllerToPresent: UIViewController, completion: ((Bool) -> Void)? = nil) {
         presentArgumentStack.append(
             .init(viewControllerToPresent: viewControllerToPresent)
         )
-        completion?()
+
+        let presented = presentCompletionHandlerResults.removeFirst()
+        completion?(presented)
     }
 }
 

flutter_custom_tabs_ios/ios/Classes/CustomTabsPlugin.swift

@@ -46,15 +46,35 @@ public class CustomTabsPlugin: NSObject, FlutterPlugin, CustomTabsApi {
         completion: @escaping (Result<Void, Error>) -> Void
     ) {
         guard let options else {
-            launcher.open(url) { _ in
-                completion(.success(()))
+            launcher.open(url) { opened in
+                if opened {
+                    completion(.success(()))
+                } else {
+                    completion(.failure(
+                        FlutterError(message: "Failed to launch external browser.")
+                    ))
+                }
             }
             return
         }
 
         let safariViewController = SFSafariViewController.make(url: url, options: options)
-        launcher.present(safariViewController) {
-            completion(.success(()))
+        launcher.present(safariViewController) { presented in
+            if presented {
+                completion(.success(()))
+            } else {
+                completion(.failure(
+                    FlutterError(message: "Failed to launch SFSafariViewController.")
+                ))
+            }
         }
     }
 }
+
+extension FlutterError: Error {
+    convenience init(message: String) {
+        self.init(code: Self.erorCode, message: message, details: nil)
+    }
+
+    static let erorCode = "LAUNCH_ERROR"
+}

flutter_custom_tabs_ios/ios/Classes/Laucher.swift

@@ -11,13 +11,17 @@ open class Launcher {
         UIApplication.shared.open(url, options: options, completionHandler: completion)
     }
 
-    open func present(_ viewControllerToPresent: UIViewController, completion: (() -> Void)? = nil) {
+    open func present(_ viewControllerToPresent: UIViewController, completion: ((Bool) -> Void)? = nil) {
         if let topViewController = UIWindow.keyWindow?.topViewController() {
             dismissStack.append { [weak viewControllerToPresent] in
                 viewControllerToPresent?.dismiss(animated: true)
             }
             topViewController
-                .present(viewControllerToPresent, animated: true, completion: completion)
+                .present(viewControllerToPresent, animated: true) {
+                    completion?(true)
+                }
+        } else {
+            completion?(false)
         }
     }