fix: incorrect warning is shown when build for iOS

When you do not have iOS native source code in `<path to App_Resources>/iOS/src`, CLI shows warning that there's no modulemap and you'll not be able to use the code through JavaScript. However, there's no code at all. Skip the preparation of native source code in case there's no native sources there.

Author: rosen-vladimirov

lib/services/ios-project-service.ts

@@ -343,6 +343,7 @@ export class IOSProjectService extends projectServiceBaseLib.PlatformProjectServ
 				platformData.normalizedPlatformName,
 				constants.NATIVE_SOURCE_FOLDER
 			);
+
 			await this.prepareNativeSourceCode(constants.TNS_NATIVE_SOURCE_GROUP_NAME, resourcesNativeCodePath, projectData);
 		}
 
@@ -498,9 +499,7 @@ export class IOSProjectService extends projectServiceBaseLib.PlatformProjectServ
 		const pluginPlatformsFolderPath = pluginData.pluginPlatformsFolderPath(IOSProjectService.IOS_PLATFORM_NAME);
 
 		const sourcePath = path.join(pluginPlatformsFolderPath, "src");
-		if (this.$fs.exists(pluginPlatformsFolderPath) && this.$fs.exists(sourcePath)) {
-			await this.prepareNativeSourceCode(pluginData.name, sourcePath, projectData);
-		}
+		await this.prepareNativeSourceCode(pluginData.name, sourcePath, projectData);
 
 		await this.prepareResources(pluginPlatformsFolderPath, pluginData, projectData);
 		await this.prepareFrameworks(pluginPlatformsFolderPath, pluginData, projectData);
@@ -644,14 +643,16 @@ export class IOSProjectService extends projectServiceBaseLib.PlatformProjectServ
 	}
 
 	private async prepareNativeSourceCode(groupName: string, sourceFolderPath: string, projectData: IProjectData): Promise<void> {
-		const project = this.createPbxProj(projectData);
-		const group = this.getRootGroup(groupName, sourceFolderPath);
-		project.addPbxGroup(group.files, group.name, group.path, null, { isMain: true, filesRelativeToProject: true });
-		project.addToHeaderSearchPaths(group.path);
-		if (!this.$fs.exists(path.join(sourceFolderPath, "module.modulemap"))) {
-			this.$logger.warn(`warning: Directory ${sourceFolderPath} with native iOS source code doesn't contain a modulemap file. Metadata for it will not be generated and it will not be accessible from JavaScript. To learn more see https://docs.nativescript.org/guides/ios-source-code`);
+		if (this.$fs.exists(sourceFolderPath)) {
+			const project = this.createPbxProj(projectData);
+			const group = this.getRootGroup(groupName, sourceFolderPath);
+			project.addPbxGroup(group.files, group.name, group.path, null, { isMain: true, filesRelativeToProject: true });
+			project.addToHeaderSearchPaths(group.path);
+			if (!this.$fs.exists(path.join(sourceFolderPath, "module.modulemap"))) {
+				this.$logger.warn(`warning: Directory ${sourceFolderPath} with native iOS source code doesn't contain a modulemap file. Metadata for it will not be generated and it will not be accessible from JavaScript. To learn more see https://docs.nativescript.org/guides/ios-source-code`);
+			}
+			this.savePbxProj(project, projectData);
 		}
-		this.savePbxProj(project, projectData);
 	}
 
 	private async addExtensions(projectData: IProjectData, pluginsData: IPluginData[]): Promise<void> {