Make `flutter build ios --simulator` default to debug builds (#5540)

packages/flutter_tools/lib/src/commands/build_ios.dart

@@ -17,7 +17,15 @@ import 'build.dart';
 class BuildIOSCommand extends BuildSubCommand {
   BuildIOSCommand() {
     usesTargetOption();
-    addBuildModeFlags();
+    argParser.addFlag('debug',
+      negatable: false,
+      help: 'Build a debug version of your app (default mode for iOS simulator builds).');
+    argParser.addFlag('profile',
+      negatable: false,
+      help: 'Build a version of your app specialized for performance profiling.');
+    argParser.addFlag('release',
+      negatable: false,
+      help: 'Build a release version of your app (default mode for device builds).');
     argParser.addFlag('simulator', help: 'Build for the iOS simulator instead of the device.');
     argParser.addFlag('codesign', negatable: true, defaultsTo: true,
         help: 'Codesign the application bundle (only available on device builds).');
@@ -31,6 +39,9 @@ class BuildIOSCommand extends BuildSubCommand {
 
   @override
   Future<int> runInProject() async {
+    bool forSimulator = argResults['simulator'];
+    defaultBuildMode = forSimulator ? BuildMode.debug : BuildMode.release;
+
     await super.runInProject();
     if (getCurrentHostPlatform() != HostPlatform.darwin_x64) {
       printError('Building for iOS is only supported on the Mac.');
@@ -44,7 +55,6 @@ class BuildIOSCommand extends BuildSubCommand {
       return 1;
     }
 
-    bool forSimulator = argResults['simulator'];
     bool shouldCodesign = argResults['codesign'];
 
     if (!forSimulator && !shouldCodesign) {

packages/flutter_tools/lib/src/runner/flutter_command.dart

@@ -70,7 +70,7 @@ abstract class FlutterCommand extends Command {
   }
 
   void addBuildModeFlags({ bool defaultToRelease: true }) {
-    _defaultBuildMode = defaultToRelease ? BuildMode.release : BuildMode.debug;
+    defaultBuildMode = defaultToRelease ? BuildMode.release : BuildMode.debug;
 
     argParser.addFlag('debug',
       negatable: false,
@@ -83,6 +83,10 @@ abstract class FlutterCommand extends Command {
       help: 'Build a release version of your app${defaultToRelease ? ' (default mode)' : ''}.');
   }
 
+  set defaultBuildMode(BuildMode buildMode) {
+    _defaultBuildMode = buildMode;
+  }
+
   BuildMode getBuildMode() {
     List<bool> modeFlags = <bool>[argResults['debug'], argResults['profile'], argResults['release']];
     if (modeFlags.where((bool flag) => flag).length > 1)