Unity vs Swift (+Reality Kit) for Apple Vision Pro development
Let's compare Unity vs Swift for developing Vision Pro apps and explore their features and differences to help you choose the best tool for your spatial computing journey.
1 April, 2024
Apple Vision Pro offers a new era in spatial computing with visionOS. Developers can create experiences using a spectrum of immersion - from simple windows with 3D objects to fully immersive virtual worlds.
We’ve learned in our previous articles that the core building blocks are windows (traditional 2D app views), volumes (3D scenes with RealityKit or Unity content), and spaces (dedicated immersive environments).
Apps launch in the Shared Space alongside others but can transition to an exclusive Full Space. This flexibility allows apps to start windowed, incorporate 3D models, shift to a bounded virtual space, or immerse the user in an unbounded digital environment.
Unity and RealityKit represent two primary frameworks for creating immersive (Augmented Reality) and fully immersive (Virtual Reality) experiences on Apple Vision Pro, each catering to different development needs and preferences.
Today, we'll compare these two powerful tools for developing Vision Pro apps, exploring their features and differences to help you choose the best tool for your spatial computing journey.
Unity: an overview
Unity, a widely used cross-platform game engine, offers versatility for AR and VR development. It has powerful tools for creating 3D apps and games.
Unity introduces technologies like PolySpatial for translating Unity materials and shaders to RealityKit, facilitating the integration of Unity-developed apps into the AR full space or shared space of VisionOS. PolySpatial, for example, was made specifically for Apple's VisionOS, and it helps build apps that use VisionOS features like see-through camera views and foveated rendering.
Unity's strengths lie in its broad compatibility, supporting features such as volumetric cameras, hand tracking, and instant preview functionalities with the Play device feature. For VR, Unity uses its Universal Render Pipeline for optimized performance, incorporating foveated rendering and supporting the XR Interaction Toolkit for cross-platform hand-tracking capabilities.
A big plus for Unity is that apps and games made with it can work on different devices without needing a lot of changes to the code. However, matching the look and feel of Apple can be tricky with Unity.
Overall, Unity is great for experienced developers building 3D and spatial apps, games, visualizations, Spaces, and Volumes for VisionOS. It has lots of learning resources and special effects features. However, less experienced developers may find Unity challenging to learn compared to other options.
Swift (RealityKit): an overview
On the other hand, RealityKit and other Apple's native frameworks offer a tightly integrated development environment within Xcode, emphasizing seamless integration with SwiftUI for 3D content preview and interaction.
SwiftUI, Apple's contemporary UI toolkit, is an optimal resource for crafting applications on visionOS. When used alongside RealityKit, SwiftUI enables the design of 3D components within applications, making it a go-to option for new visionOS projects. The integration of UIKit with SwiftUI ensures a seamless experience for developers acquainted with iOS and iPadOS app development.
RealityKit, Apple's 3D rendering engine, is a powerful tool for presenting 3D content, animations, and visual effects. It adapts to physical lighting conditions, creates realistic shadows, and facilitates the development of impressive visual effects, among other features. RealityKit has embraced MaterialX, an industry standard for specifying surface and geometry shaders.
ARKit, another crucial component of visionOS, enables immersive interactions and supports the creation of custom gestures. Its capabilities extend to understanding a user's surroundings on Apple Vision Pro, offering new avenues for applications to interact with their environment.
While the combination of SwiftUI and RealityKit provides an intuitive, native feel and facilitates the creation of window-type applications, it may fall short for applications with more extensive 3D content. For 3D-heavy spatial applications, developers might find RealityKit more favorable, despite its limitations, such as a basic particle emitter and less code reusability across multiple devices.
Unity vs Swift: comparison and considerations
The choice between Unity and RealityKit for Apple Vision Pro development depends on several factors: the desired level of cross-platform compatibility, the specific requirements of the immersive experience being developed, and the developer's familiarity with each ecosystem.
Unity stands out for its cross-platform capabilities and extensive support for immersive content creation, while RealityKit and Apple's native frameworks excel in providing a unified and optimized development experience for Apple devices.
Weigh the following considerations against your project needs and expertise to select the most suitable framework.
Cross-platform compatibility
You need to consider where your application needs to operate. Unity is highlighted for its strength in cross-platform development beyond the Apple ecosystem, making it an attractive choice for projects targeting a wide range of devices, including VR headsets like Oculus Quest.
In contrast, RealityKit and Apple’s native frameworks are optimized for the Apple ecosystem, making them ideal for developers aiming to create experiences that are exclusive to Apple devices and benefit from deep integration with iOS, macOS, and VisionOS.
Developer experience
The ease of development based on a developer's background is another crucial consideration. For developers with a strong foundation in iOS development and Swift, Apple’s native frameworks offer a familiar and cohesive environment that could accelerate development.
Developers coming from a game development or cross-platform background might find Unity’s environment more in line with their expertise, potentially easing the learning curve and improving development speed.
Technological maturity and integration
We already mentioned PolySpatial, a new technology by Unity designed to bridge Unity-developed content with RealityKit, facilitating AR experiences on VisionOS. Some sources hint at potential “friction” due to the inherent challenges in melding two distinct ecosystems.
The level of technological maturity and the smoothness of integration between Unity and RealityKit via PolySpatial could be a factor for developers to monitor.
Speed to MVP
The choice between Unity and RealityKit could also depend on which platform allows a developer to prototype and iterate their ideas more rapidly. This consideration might lean in favor of the developer’s familiarity with the platform and the availability of features that expedite the development process for their specific project needs.
Future-proofing and community support
Finally, it’s important to consider the future trajectory of each platform and the community and developer support available. Unity’s longstanding presence and extensive user base offer a wealth of resources and a robust community for troubleshooting and innovation.
Apple’s platforms, known for their high-quality developer tools and documentation, promise a streamlined and optimized development experience, potentially offering faster updates and more integrated features for Apple’s hardware.
Principles for choosing a tech stack for Apple Vision Pro
When selecting the optimal technology stack for developing applications for Apple's Vision Pro augmented reality headset, here’s what you should consider.
Scalability
The augmented reality field gets new innovations and advancements almost every week. Choose a tech stack that can adapt to these changes, enabling your application to scale and incorporate future trends. Platforms with a broader focus on AR/VR across multiple devices may offer more agility in pivoting to new developments.
Hardware optimization
Even though Vision Pro does have powerful hardware capabilities, you need to select a stack that efficiently utilizes these resources without causing performance issues like overheating or lags. Native tools like SwiftUI and RealityKit, designed specifically for Apple's ecosystem, are optimized for power efficiency and seamless integration with the device's hardware.
Security and data protection
Apple's ecosystem is renowned for its robust security protocols. Choosing a tech stack that more seamlessly integrates with the device's built-in security measures can better ensure user data protection and compliance with Apple's guidelines.
Expertise and community support
While Apple's native tools are capable enough, third-party platforms like Unity boast vast developer communities, offering countless resources, plugins, and troubleshooting guides. Consider the depth of expertise and community support available for your chosen stack, as this can significantly impact development efficiency and problem-solving.
Compatibility
Although specialization is important, cross-platform compatibility can be a significant advantage when you get wider reach and future-proofing against market shifts. Your chosen tech stack should be adaptable enough to work across different hardware ecosystems, making your application better reach a broader audience.
End-user experience
Ultimately, the success of any application depends on its user experience. The chosen tech stack and development strategy should prioritize intuitive interfaces, seamless transitions between AR and VR, and optimal performance, even as the application scales. An experienced team with expertise in building augmented reality products is key to achieving this.
Cost-effectiveness and maintenance
While Apple's native tools are bundled with the developer account, third-party platforms may have licensing costs, especially for targeting multiple platforms. Additionally, consider the long-term maintenance and update costs, as native tools will receive regular updates aligned with Apple's OS updates, ensuring faster bug patches.
Conclusion
The Apple Vision Pro platform offers a unique opportunity for developers to create immersive spatial experiences. As we've explored, choosing between Unity and Apple's native frameworks like RealityKit and SwiftUI involves weighing various factors.
While Unity excels in cross-platform capabilities and extensive 3D content creation tools, Apple's native frameworks provide a seamless and optimized development experience made specifically for the Apple ecosystem.
By carefully considering the principles discussed above, you can make an informed choice about choosing a tech stack that best suits your project needs.
P.S. Don't forget to also check the design considerations for Vision Pro apps.
If you're interested in learning more about how we can help you use the capabilities of Apple Vision Pro to build your next spatial computing application, feel free to reach out to us at Merge.
