[file_selector] Convert iOS to Swift and SPM (flutter#6755)

Converts the plugin and its tests to Swift, and re-adds the SPM support that was reverted due to modulemap issues.

In order to avoid the ugliness and loss of type saftey of using associated objects in the Swift version, this replaces that with a bridge object that serves as a delegate instead of the plugin, and manages its own lifetime in coordination with the plugin.

While this is one PR, the conversion was done in individual steps, each of which is a commit:
- Rewrite just the tests in Swift, with no implementation changes, ensuring that everything still passed.
- Rewrite the implementation in Swift, changing the tests only as necessary for the structural changes to the implementation due to the removal of associated objects
- Re-add SPM

The changes in the generated Dart files are just due to updating to the latest version of Pigeon (to avoid writing the Swift implementation against an older version of the Swift API, and then having to update again later for breaking changes).

Part of flutter#119015
Fixes flutter#146903

Author: stuartmorgan-g

packages/file_selector/file_selector_ios/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 0.5.3
+
+* Converts implementation to Swift.
+* Re-adds Swift Package Manager compatibility.
+
 ## 0.5.2+1
 
 * Temporarily remove Swift Package Manager compatibility to resolve issues with Cocoapods builds.

packages/file_selector/file_selector_ios/example/ios/Runner.xcodeproj/project.pbxproj

@@ -9,13 +9,13 @@
 /* Begin PBXBuildFile section */
 		1498D2341E8E89220040F4C2 /* GeneratedPluginRegistrant.m in Sources */ = {isa = PBXBuildFile; fileRef = 1498D2331E8E89220040F4C2 /* GeneratedPluginRegistrant.m */; };
 		21160A929DC757957DE39F1E /* Pods_Runner.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 000792269CB6B9FE88AC567C /* Pods_Runner.framework */; };
+		337EF9CE2BF7945F0079FB1A /* FileSelectorTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 337EF9CD2BF7945F0079FB1A /* FileSelectorTests.swift */; };
 		3B3967161E833CAA004F5970 /* AppFrameworkInfo.plist in Resources */ = {isa = PBXBuildFile; fileRef = 3B3967151E833CAA004F5970 /* AppFrameworkInfo.plist */; };
 		6165A2F80DFA224EAF50A1D5 /* Pods_RunnerTests.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = AC3841659BF3693FAC5A2F8F /* Pods_RunnerTests.framework */; };
 		74858FAF1ED2DC5600515810 /* AppDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 74858FAE1ED2DC5600515810 /* AppDelegate.swift */; };
 		97C146FC1CF9000F007C117D /* Main.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = 97C146FA1CF9000F007C117D /* Main.storyboard */; };
 		97C146FE1CF9000F007C117D /* Assets.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = 97C146FD1CF9000F007C117D /* Assets.xcassets */; };
 		97C147011CF9000F007C117D /* LaunchScreen.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = 97C146FF1CF9000F007C117D /* LaunchScreen.storyboard */; };
-		C71AE4C8281C6B6B0086307A /* FileSelectorTests.m in Sources */ = {isa = PBXBuildFile; fileRef = C71AE4C5281C6B530086307A /* FileSelectorTests.m */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -45,6 +45,7 @@
 		000792269CB6B9FE88AC567C /* Pods_Runner.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = Pods_Runner.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		1498D2321E8E86230040F4C2 /* GeneratedPluginRegistrant.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = GeneratedPluginRegistrant.h; sourceTree = "<group>"; };
 		1498D2331E8E89220040F4C2 /* GeneratedPluginRegistrant.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = GeneratedPluginRegistrant.m; sourceTree = "<group>"; };
+		337EF9CD2BF7945F0079FB1A /* FileSelectorTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FileSelectorTests.swift; sourceTree = "<group>"; };
 		3B3967151E833CAA004F5970 /* AppFrameworkInfo.plist */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.xml; name = AppFrameworkInfo.plist; path = Flutter/AppFrameworkInfo.plist; sourceTree = "<group>"; };
 		4A27CC0DB4EF6669B637A1E8 /* Pods-RunnerTests.debug.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-RunnerTests.debug.xcconfig"; path = "Target Support Files/Pods-RunnerTests/Pods-RunnerTests.debug.xcconfig"; sourceTree = "<group>"; };
 		5667547C6832727A744371E2 /* Pods-RunnerTests.release.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-RunnerTests.release.xcconfig"; path = "Target Support Files/Pods-RunnerTests/Pods-RunnerTests.release.xcconfig"; sourceTree = "<group>"; };
@@ -63,7 +64,6 @@
 		97C147021CF9000F007C117D /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
 		AC3841659BF3693FAC5A2F8F /* Pods_RunnerTests.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = Pods_RunnerTests.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		C71AE4B6281C6A090086307A /* RunnerTests.xctest */ = {isa = PBXFileReference; explicitFileType = wrapper.cfbundle; includeInIndex = 0; path = RunnerTests.xctest; sourceTree = BUILT_PRODUCTS_DIR; };
-		C71AE4C5281C6B530086307A /* FileSelectorTests.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = FileSelectorTests.m; sourceTree = "<group>"; };
 		F818CE2D7CDF8AFF94707327 /* Pods-Runner.release.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-Runner.release.xcconfig"; path = "Target Support Files/Pods-Runner/Pods-Runner.release.xcconfig"; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
@@ -150,7 +150,7 @@
 		C71AE4C4281C6B370086307A /* RunnerTests */ = {
 			isa = PBXGroup;
 			children = (
-				C71AE4C5281C6B530086307A /* FileSelectorTests.m */,
+				337EF9CD2BF7945F0079FB1A /* FileSelectorTests.swift */,
 			);
 			path = RunnerTests;
 			sourceTree = "<group>";
@@ -223,6 +223,7 @@
 					};
 					C71AE4B5281C6A090086307A = {
 						CreatedOnToolsVersion = 13.1;
+						LastSwiftMigration = 1510;
 						TestTargetID = 97C146ED1CF9000F007C117D;
 					};
 				};
@@ -376,7 +377,7 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
-				C71AE4C8281C6B6B0086307A /* FileSelectorTests.m in Sources */,
+				337EF9CE2BF7945F0079FB1A /* FileSelectorTests.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -636,6 +637,7 @@
 			baseConfigurationReference = 4A27CC0DB4EF6669B637A1E8 /* Pods-RunnerTests.debug.xcconfig */;
 			buildSettings = {
 				BUNDLE_LOADER = "$(TEST_HOST)";
+				CLANG_ENABLE_MODULES = YES;
 				CODE_SIGN_STYLE = Automatic;
 				CURRENT_PROJECT_VERSION = 1;
 				GENERATE_INFOPLIST_FILE = YES;
@@ -647,6 +649,8 @@
 				MARKETING_VERSION = 1.0;
 				PRODUCT_BUNDLE_IDENTIFIER = dev.flutter.plugins.FileSelectorTests;
 				PRODUCT_NAME = "$(TARGET_NAME)";
+				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
+				SWIFT_VERSION = 5.0;
 				TEST_HOST = "$(BUILT_PRODUCTS_DIR)/Runner.app/Runner";
 			};
 			name = Debug;
@@ -659,6 +663,7 @@
 				BUNDLE_LOADER = "$(TEST_HOST)";
 				CLANG_ANALYZER_NUMBER_OBJECT_CONVERSION = YES_AGGRESSIVE;
 				CLANG_CXX_LANGUAGE_STANDARD = "gnu++17";
+				CLANG_ENABLE_MODULES = YES;
 				CLANG_ENABLE_OBJC_WEAK = YES;
 				CLANG_WARN_DOCUMENTATION_COMMENTS = YES;
 				CLANG_WARN_QUOTED_INCLUDE_IN_FRAMEWORK_HEADER = YES;
@@ -678,6 +683,7 @@
 				PRODUCT_BUNDLE_IDENTIFIER = dev.flutter.plugins.FileSelectorTests;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SWIFT_EMIT_LOC_STRINGS = NO;
+				SWIFT_VERSION = 5.0;
 				TARGETED_DEVICE_FAMILY = "1,2";
 				TEST_HOST = "$(BUILT_PRODUCTS_DIR)/Runner.app/Runner";
 			};
@@ -691,6 +697,7 @@
 				BUNDLE_LOADER = "$(TEST_HOST)";
 				CLANG_ANALYZER_NUMBER_OBJECT_CONVERSION = YES_AGGRESSIVE;
 				CLANG_CXX_LANGUAGE_STANDARD = "gnu++17";
+				CLANG_ENABLE_MODULES = YES;
 				CLANG_ENABLE_OBJC_WEAK = YES;
 				CLANG_WARN_DOCUMENTATION_COMMENTS = YES;
 				CLANG_WARN_QUOTED_INCLUDE_IN_FRAMEWORK_HEADER = YES;
@@ -710,6 +717,7 @@
 				PRODUCT_BUNDLE_IDENTIFIER = dev.flutter.plugins.FileSelectorTests;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SWIFT_EMIT_LOC_STRINGS = NO;
+				SWIFT_VERSION = 5.0;
 				TARGETED_DEVICE_FAMILY = "1,2";
 				TEST_HOST = "$(BUILT_PRODUCTS_DIR)/Runner.app/Runner";
 			};

packages/file_selector/file_selector_ios/example/ios/Runner.xcodeproj/xcshareddata/xcschemes/Runner.xcscheme

@@ -5,6 +5,24 @@
    <BuildAction
       parallelizeBuildables = "YES"
       buildImplicitDependencies = "YES">
+      <PreActions>
+         <ExecutionAction
+            ActionType = "Xcode.IDEStandardExecutionActionsCore.ExecutionActionType.ShellScriptAction">
+            <ActionContent
+               title = "Run Prepare Flutter Framework Script"
+               scriptText = "/bin/sh &quot;$FLUTTER_ROOT/packages/flutter_tools/bin/xcode_backend.sh&quot; prepare&#10;">
+               <EnvironmentBuildable>
+                  <BuildableReference
+                     BuildableIdentifier = "primary"
+                     BlueprintIdentifier = "97C146ED1CF9000F007C117D"
+                     BuildableName = "Runner.app"
+                     BlueprintName = "Runner"
+                     ReferencedContainer = "container:Runner.xcodeproj">
+                  </BuildableReference>
+               </EnvironmentBuildable>
+            </ActionContent>
+         </ExecutionAction>
+      </PreActions>
       <BuildActionEntries>
          <BuildActionEntry
             buildForTesting = "YES"

packages/file_selector/file_selector_ios/example/ios/Runner/AppDelegate.swift

@@ -5,7 +5,7 @@
 import Flutter
 import UIKit
 
-@UIApplicationMain
+@main
 @objc class AppDelegate: FlutterAppDelegate {
   override func application(
     _ application: UIApplication,

packages/file_selector/file_selector_ios/example/ios/RunnerTests/FileSelectorTests.m

@@ -0,0 +1,85 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import XCTest
+
+@testable import file_selector_ios
+
+final class TestViewPresenter: ViewPresenter {
+  public var presentedController: UIViewController?
+
+  func present(
+    _ viewControllerToPresent: UIViewController, animated: Bool, completion: (() -> Void)? = nil
+  ) {
+    presentedController = viewControllerToPresent
+  }
+}
+
+class FileSelectorTests: XCTestCase {
+  func testPickerPresents() throws {
+    let plugin = FileSelectorPlugin()
+    let picker = UIDocumentPickerViewController(documentTypes: [], in: UIDocumentPickerMode.import)
+    let presenter = TestViewPresenter()
+    plugin.documentPickerViewControllerOverride = picker
+    plugin.viewPresenterOverride = presenter
+
+    plugin.openFile(
+      config: FileSelectorConfig(utis: [], allowMultiSelection: false)
+    ) { _ in }
+
+    XCTAssertEqual(plugin.pendingCompletions.count, 1)
+    XCTAssertTrue(picker.delegate === plugin.pendingCompletions.first)
+    XCTAssertTrue(presenter.presentedController === picker)
+  }
+
+  func testReturnsPickedFiles() throws {
+    let plugin = FileSelectorPlugin()
+    let picker = UIDocumentPickerViewController(documentTypes: [], in: UIDocumentPickerMode.import)
+    plugin.documentPickerViewControllerOverride = picker
+    plugin.viewPresenterOverride = TestViewPresenter()
+    let completionWasCalled = expectation(description: "completion")
+
+    plugin.openFile(
+      config: FileSelectorConfig(utis: [], allowMultiSelection: false)
+    ) { result in
+      switch result {
+      case .success(let paths):
+        XCTAssertEqual(paths, ["/file1.txt", "/file2.txt"])
+      case .failure(let error):
+        XCTFail("\(error)")
+      }
+      completionWasCalled.fulfill()
+    }
+    plugin.pendingCompletions.first!.documentPicker(
+      picker,
+      didPickDocumentsAt: [URL(string: "file:///file1.txt")!, URL(string: "file:///file2.txt")!])
+
+    waitForExpectations(timeout: 30.0)
+    XCTAssertTrue(plugin.pendingCompletions.isEmpty)
+  }
+
+  func testCancellingPickerReturnsEmptyList() throws {
+    let plugin = FileSelectorPlugin()
+    let picker = UIDocumentPickerViewController(documentTypes: [], in: UIDocumentPickerMode.import)
+    plugin.documentPickerViewControllerOverride = picker
+    plugin.viewPresenterOverride = TestViewPresenter()
+    let completionWasCalled = expectation(description: "completion")
+
+    plugin.openFile(
+      config: FileSelectorConfig(utis: [], allowMultiSelection: false)
+    ) { result in
+      switch result {
+      case .success(let paths):
+        XCTAssertEqual(paths.count, 0)
+      case .failure(let error):
+        XCTFail("\(error)")
+      }
+      completionWasCalled.fulfill()
+    }
+    plugin.pendingCompletions.first!.documentPickerWasCancelled(picker)
+
+    waitForExpectations(timeout: 30.0)
+    XCTAssertTrue(plugin.pendingCompletions.isEmpty)
+  }
+}

packages/file_selector/file_selector_ios/example/ios/RunnerTests/FileSelectorTests.swift

@@ -13,11 +13,14 @@ Displays the native iOS document picker.
   s.license          = { :type => 'BSD', :file => '../LICENSE' }
   s.author           = { 'Flutter Dev Team' => 'flutter-dev@googlegroups.com' }
   s.source           = { :http => 'https://github.com/flutter/packages/tree/main/packages/file_selector/file_selector_ios' }
-  s.source_files = 'file_selector_ios/Sources/file_selector_ios/**/*.{h,m}'
-  s.module_map = 'file_selector_ios/Sources/file_selector_ios/include/cocoapods_file_selector_ios.modulemap'
+  s.source_files = 'file_selector_ios/Sources/file_selector_ios/**/*.swift'
   s.dependency 'Flutter'
   s.platform = :ios, '12.0'
   s.pod_target_xcconfig = { 'DEFINES_MODULE' => 'YES' }
   s.swift_version = '5.0'
+  s.xcconfig = {
+    'LIBRARY_SEARCH_PATHS' => '$(TOOLCHAIN_DIR)/usr/lib/swift/$(PLATFORM_NAME)/ $(SDKROOT)/usr/lib/swift',
+    'LD_RUNPATH_SEARCH_PATHS' => '/usr/lib/swift',
+  }
   s.resource_bundles = {'file_selector_ios_privacy' => ['file_selector_ios/Sources/file_selector_ios/Resources/PrivacyInfo.xcprivacy']}
 end

packages/file_selector/file_selector_ios/ios/file_selector_ios.podspec

@@ -0,0 +1,31 @@
+// swift-tools-version: 5.9
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import PackageDescription
+
+let package = Package(
+  name: "file_selector_ios",
+  platforms: [
+    .iOS("12.0")
+  ],
+  products: [
+    .library(name: "file-selector-ios", targets: ["file_selector_ios"])
+  ],
+  dependencies: [],
+  targets: [
+    .target(
+      name: "file_selector_ios",
+      dependencies: [],
+      resources: [
+        .process("Resources")
+      ],
+      cSettings: [
+        .headerSearchPath("include/file_selector_ios")
+      ]
+    )
+  ]
+)