How to compile an iOS app for Simulator

Hari Mahesh

Compiling an iOS app for the simulator involves several steps, each critical to ensuring the app runs smoothly. This guide helps you understand the process of setting up the development environment for compiling the iOS app to run on a simulator.

Setting Up Development Environment

Let’s start by setting up the development environment. There are multiple steps involved in this.

Step 1: Install Xcode

The Xcode is Apple’s Integrated Development Environment (IDE) for macOS. Using Xcode, you can develop apps for different iOS form factors. Xcode provides all the necessary plugins and components required to create apps for iPhone, iPad, Apple Watch, and Mac. To set up Xcode, follow these steps:

• Download Xcode: Visit the Mac App Store and search for Xcode. Download and install Xcode.
• Set Up Your Apple ID: Once installed, open Xcode, go to the Preferences (Xcode>Preferences), and add your Apple ID under the Accounts tab.

Step 2: Xcode Command Line Tools

xcode-select --install

Step 3: Creating a New Xcode Project

The next step is to create a new Xcode Project; here are the steps:

• Open Xcode: Launch Xcode from your Applications folder.
• Start a New Project: Select “Create a new Xcode project” from the welcome window.
• Choose a Template: Select a template for your project. For most iOS apps, the “App” template under the iOS tab is suitable.
• Configure Your Project: Enter your project’s name, organization name, and bundle identifier. Choose Swift or Objective-C as the language and ensure “Use SwiftUI” or “Use Storyboards” is selected based on your preference.
• Save Your Project: Choose a location to save your project and click “Create.”

Step 4: Configuring the Simulator

The Simulator helps to run your iOS app on different iOS emulators on your Mac machine. This helps you to test and verify that the app you developed works on different form factors based on your requirements. Now, let’s configure the Simulator.

• Choose a Simulator Device: In Xcode, select your project in the Project Navigator. Click the target device near the Run button in the toolbar and choose an iOS Simulator device (e.g., iPhone 15, iPhone SE).
• Customizing Simulator Settings: You can further customize your simulator’s settings by opening the Simulator app (found in the Applications folder under Xcode > Contents > Developer > Applications).

Our next step will be compiling the iOS App for Simulator.

Compiling Your iOS App for the Simulator

There are a few steps to compile the app. Let’s go through each one.

Step 1: Selecting the Build Target

Before we compile the app, we need to ensure that the project is set to build for the Simulator.

• Scheme Configuration: In Xcode, go to Product > Scheme > Edit Scheme. Ensure that the “Run” action’s Build Configuration is set to “Debug“.
• Simulator Device: In the toolbar, select the desired Simulator device.

Step 2: Building the App

• Open Terminal: Launch the Terminal application on your macOS.
• Navigate to Your Project Directory: Use the ‘cd‘ command to navigate to the root directory of your Xcode project. For example:

  cd path/to/your/xcode/project

• Run the Build Command: Use the ‘xcodebuild‘ command to compile your app for the simulator. Here’s an example command:

  xcrun xcodebuild \
  -scheme YourSchemeName \
  -project YourProjectName.xcodeproj \
  -configuration Debug \
  -destination 'platform=iOS Simulator,name=iPhone 15,OS=latest' \
  -derivedDataPath build

  Replace the placeholders:
  1. YourSchemeName: The scheme of your project.
  2. YourProjectName.xcodeproj: The name of your Xcode project file.
  3. iPhone 15: The simulator device you want to build for (e.g., iPhone 15, iPhone SE, etc.).
  4. OS=latest: The iOS version you want to simulate (e.g., 17.5.1, 16.7.8, latest).
  Understanding the Build command:
  1. xcrun xcodebuild: This invokes the Xcode build tool.
  2. -scheme YourSchemeName: Specifies the scheme to build.
  3. -project YourProjectName.xcodeproj: Points to the project file.
  4. -configuration Debug: Sets the build configuration (Debug or Release).
  5. -destination ‘platform=iOS Simulator,name=iPhone 15,OS=latest’: Defines the build destination, targeting a specific simulator.
  6. -derivedDataPath build: Specifies the directory to store build products and intermediate files.
  7. Handling Build Errors: If there are errors, Xcode will display them in the Issue Navigator. Address these errors by following the suggestions provided or consulting the documentation.

Running the App on the Simulator

Once the build is successful, the app will launch on the selected Simulator device:

• Launching the App: Once the app building process is complete, the simulator will open automatically and the app will be opened. You can interact with the simulator just like interacting with a physical device.
• Debugging Tools: Use Xcode’s debugging tools to set breakpoints, inspect variables, and step through your code.

Optimizing Your App for the Simulator

Since we are running a simulator on our machine, optimizing the app is mandatory. Let’s see how we can optimize the app.

Performance Profiling

Use Xcode’s Instruments to profile and optimize your app:

• Launching Instruments: Go to Product > Profile or press Command + I. Select a profiling template, such as Time Profiler or Allocations.
• Analyzing Performance: Use Instruments to identify performance bottlenecks and memory leaks.

Simulator-Specific Optimizations

• Simulator vs. Real Device: Remember that the Simulator runs x86_64 architecture, while real devices use ARM. Performance may differ.
• Mocking Hardware Features: The Simulator can mock features like GPS, camera, and accelerometer. Use these to test hardware-specific functionality.

Testing using Intelligent Test Automation

testRigor is an intelligent tool that uses generative AI to make test case creation, execution, and maintenance easy on its intuitive cloud platform. It allows you to create various types of tests for different types of apps and platforms in plain English without requiring any kind of coding knowledge. You can easily and quickly automate web, mobile (hybrid, native), desktop, API, database, file handling, QR code, Captcha resolution, email, phone, SMS, 2FA, and more complex scenarios in just plain English (or any other natural language).

Using testRigor, you can test mobile applications on real devices and emulators. Read a comparison of iOS emulators/simulators with real iOS devices. With testRigor, you can test on multiple devices in parallel, thereby covering a large number of devices in a short time. Read this step-by-step guide to learn How to Generate a File for testRigor iOS Simulators.

By integrating testRigor with your CI/CD pipeline, you can ensure continuous testing and quick feedback on your app’s performance and functionality. Here’s a full list of testRigor’s powerful capabilities and its incredible benefits.

Conclusion

Building an iOS app in a simulator and testing it against its functionalities is the primary step in iOS testing. To make it happen, the developer or tester should know how to configure the environment and build the app. By performing this, we can ensure the app meets the requirements. Integrating with tools like testRigor can make the testing much faster. With testRigor, even manual testers can create and execute test scripts faster. This combination of thorough manual setup and advanced automated testing leads to a robust development workflow, ensuring your app is well-tested and ready for deployment.

“We spent so much time on maintenance when using Selenium, and we spend nearly zero time with maintenance using testRigor.”

Keith Powe VP Of Engineering - IDT