Ensure proper initialization and UI setup of iOS view controllers by testing their load using Storyboards, XIBs, and code-based approaches

Introduction

When developing iOS applications, testing the load of view controllers is a crucial step to ensure that they are properly initialized and their user interfaces are set up correctly. In this article, we will explore different approaches to testing view controller load using Storyboards, XIBs, and code-based view controllers. We will provide code examples for each approach to demonstrate the testing process and offer best practices along the way.

Testing Load with Storyboards

Storyboards offer a visual way of designing user interfaces and connecting view controllers. To test the load of a view controller created using Storyboards.

func test_loading() {
  let sb = UIStoryboard(name: "Main", bundle: nil)
  let sut: StoryboardBasedViewController = sb.instantiateViewController(identifier: String(describing: StoryboardBasedViewController.self))
    
  sut.loadViewIfNeeded()
    
  XCTAssertNotNil(sut.label)
}

In the code snippet above, we first create an instance of the storyboard (sb) using its name. We then instantiate the view controller (sut) by providing its identifier. Finally, we call loadViewIfNeeded() to ensure that the view is loaded and its outlets are connected. Here, we assert that the label outlet of the view controller is not nil, indicating that the view controller was properly loaded.

Testing Load with XIBs

XIBs provide a way to create reusable user interface components. When testing the load of a view controller created using XIBs.

func test_loading() {
  let sut = XIBBasedViewController()
    
  sut.loadViewIfNeeded()
    
  XCTAssertNotNil(sut.label)
}

In the above code snippet, we directly create an instance of the view controller (sut). We then call loadViewIfNeeded() to ensure that the view is loaded and its outlets are connected. Finally, we assert that the label outlet of the view controller is not nil, indicating that the view controller was successfully loaded.

Testing Load with Code-Based View Controllers

Code-based view controllers provide flexibility and control over the view hierarchy. To test the load of a code-based view controller

func test_loading() {
  let sut = CodeBasedViewController(data: "DUMMY")
    
  sut.loadViewIfNeeded()
}

In the code snippet above, we create an instance of the view controller (sut) by passing any necessary dependencies, such as the data parameter in this case. We then call loadViewIfNeeded() to ensure that the view is loaded and any setup logic is executed. Since we are not testing any specific outlets or UI elements in this example, we do not include any assertions. However, you can add assertions as needed based on your specific testing requirements.

When testing code-based view controllers, one advantage is that it’s easier to have our initializers compared to Storyboard or XIB-based view controllers. This gives us more flexibility in providing any necessary dependencies or custom data during testing. It is common to encounter dependencies that require certain data, even if that data is not necessary for the specific test case. In such situations, it is helpful to provide dummy data, often using “dummy” for strings and 0 for integers, another approach is to create a variable with the prefix dummy and pass it to fulfill the requirements of the dependencies without impacting the actual test scenario. This approach helps other developers understand that the data is required for creating the instance but is unnecessary for the test itself.

Best Practices for View Controller Load Testing

Regardless of the approach you choose, here are some best practices to consider when testing view controller load:

  1. Mock Dependencies: If your view controller relies on dependencies, use mock objects or dependency injection techniques to isolate and control their behavior during testing.
  2. Test Lifecycle Methods: Test the behavior of lifecycle methods such as viewDidLoad(), viewWillAppear(), and viewDidAppear() to ensure that they are called and executed correctly.
  3. Measure Performance: Monitor the performance of your view controller load tests to detect any potential bottlenecks or performance issues.

Conclusion

Testing the load of view controllers is an essential aspect of iOS development to ensure proper initialization and user interface setup. In this article, we explored different approaches for testing view controller load using Storyboards, XIBs, and code-based view controllers. By following best practices, such as mocking dependencies and testing lifecycle methods, we can create robust tests that validate the correct loading of view controllers.

Whether you prefer Storyboards for visual design, XIBs for reusable components, or code-based view controllers for flexibility, each approach has its testing considerations. Remember to adapt your testing strategies based on the specific requirements and dependencies of your view controllers.

By investing time and effort into thorough view controller load testing, you can identify and fix potential issues early on, ensuring a smooth user experience in your iOS applications.

I hope this article helps you, I’ll appreciate it if you can share it, #HappyTesting and #HappyCoding👨‍💻.

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