Support route on ios engine (flutter/engine#31555)

engine/src/flutter/common/settings.h

@@ -107,6 +107,8 @@ struct Settings {
   std::string isolate_snapshot_instr_path;  // deprecated
   MappingCallback isolate_snapshot_instr;
 
+  std::string route;
+
   // Returns the Mapping to a kernel buffer which contains sources for dart:*
   // libraries.
   MappingCallback dart_library_sources_kernel;

engine/src/flutter/shell/common/switches.cc

@@ -356,6 +356,8 @@ Settings SettingsFromCommandLine(const fml::CommandLine& command_line) {
   command_line.GetOptionValue(FlagForSwitch(Switch::VmSnapshotData),
                               &vm_snapshot_data_filename);
 
+  command_line.GetOptionValue(FlagForSwitch(Switch::Route), &settings.route);
+
   std::string vm_snapshot_instr_filename;
   command_line.GetOptionValue(FlagForSwitch(Switch::VmSnapshotInstructions),
                               &vm_snapshot_instr_filename);

engine/src/flutter/shell/common/switches.h

@@ -105,6 +105,9 @@ DEF_SWITCH(EnableSoftwareRendering,
            "Enable rendering using the Skia software backend. This is useful "
            "when testing Flutter on emulators. By default, Flutter will "
            "attempt to either use OpenGL, Metal, or Vulkan.")
+DEF_SWITCH(Route,
+           "route",
+           "Start app with an specific route defined on the framework")
 DEF_SWITCH(SkiaDeterministicRendering,
            "skia-deterministic-rendering",
            "Skips the call to SkGraphics::Init(), thus avoiding swapping out "

engine/src/flutter/shell/common/switches_unittests.cc

@@ -46,5 +46,15 @@ TEST(SwitchesTest, SkiaTraceAllowlistFlag) {
 #endif
 }
 
+TEST(SwitchesTest, RouteParsedFlag) {
+  fml::CommandLine command_line =
+      fml::CommandLineFromInitializerList({"command", "--route=/animation"});
+  Settings settings = SettingsFromCommandLine(command_line);
+  EXPECT_EQ(settings.route, "/animation");
+  command_line = fml::CommandLineFromInitializerList({"command", "--route"});
+  settings = SettingsFromCommandLine(command_line);
+  EXPECT_TRUE(settings.route.empty());
+}
+
 }  // namespace testing
 }  // namespace flutter

engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterEngine.mm

@@ -695,6 +695,13 @@ static void SetEntryPoint(flutter::Settings* settings, NSString* entrypoint, NSS
   self.initialRoute = initialRoute;
 
   auto settings = [_dartProject.get() settings];
+  if (initialRoute != nil) {
+    self.initialRoute = initialRoute;
+  } else if (settings.route.empty() == false) {
+    self.initialRoute = [NSString stringWithCString:settings.route.c_str()
+                                           encoding:NSUTF8StringEncoding];
+  }
+
   FlutterView.forceSoftwareRendering = settings.enable_software_rendering;
 
   auto platformData = [_dartProject.get() defaultPlatformData];

engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterEngineTest.mm

@@ -159,6 +159,26 @@ FLUTTER_ASSERT_ARC
                                        message:encodedSetInitialRouteMethod]);
 }
 
+- (void)testInitialRouteSettingsSendsNavigationMessage {
+  id mockBinaryMessenger = OCMClassMock([FlutterBinaryMessengerRelay class]);
+
+  auto settings = FLTDefaultSettingsForBundle();
+  settings.route = "test";
+  FlutterDartProject* project = [[FlutterDartProject alloc] initWithSettings:settings];
+  FlutterEngine* engine = [[FlutterEngine alloc] initWithName:@"foobar" project:project];
+  [engine setBinaryMessenger:mockBinaryMessenger];
+  [engine run];
+
+  // Now check that an encoded method call has been made on the binary messenger to set the
+  // initial route to "test".
+  FlutterMethodCall* setInitialRouteMethodCall =
+      [FlutterMethodCall methodCallWithMethodName:@"setInitialRoute" arguments:@"test"];
+  NSData* encodedSetInitialRouteMethod =
+      [[FlutterJSONMethodCodec sharedInstance] encodeMethodCall:setInitialRouteMethodCall];
+  OCMVerify([mockBinaryMessenger sendOnChannel:@"flutter/navigation"
+                                       message:encodedSetInitialRouteMethod]);
+}
+
 - (void)testPlatformViewsControllerRenderingMetalBackend {
   FlutterEngine* engine = [[FlutterEngine alloc] init];
   [engine run];