Create helper SwiftUI and UIKit Views

[andyf-canva]

Issue here -> #3

From a discussion between @tinyjin and @andyf-canva...

I have a question, Is there a component like based on UIView or SwiftUI?
Unfortunately not 😢. ... if people want to use this API then they need to manually iterate through the frames and create a LottieRenderer themselves. Which is a good point to make: if most consumers of Lottie expect to be using this in a UIKit/SwiftUI context, they may struggle to use the package.

This PR introduces helper a SwiftUI View and UIKit UIView to promote easier adoption of the LottieRenderer-based rendering implementation.

TODO:

• Clean up ViewModel
• Write documentation
• Write tests
• Update documentation

[andyf-canva]

@tinyjin @hermet - just a heads up on my progress with creating these helpers views. Apologies - we've been extremely busy here at Canva so haven't had time to get to this. Will look to wrap this up over the next few weeks. 👍

[andyf-canva]

Hey folks! Sorry it's been a mad rush for the end of the year. I'll pick this back up in the New Year and can get it merged 🙏

[hermet]

@andyf-canva no worry, wish you a merry christmas!

[andyf-canva]

Another follow up, we've been so busy with our push to Canva Create I haven't had any time for this. Luckily we've got a bit of time over the next few weeks that I can spend cleaning this up.

@hermet is there still appetite for introducing this API into the core thorvg module?

[hermet]

@andyf-canva Hello, no worries! 🙂 If the PR is ready, please remove the draft status so we can start the review process. Thanks!

[Copilot]

Pull Request Overview

This PR creates helper SwiftUI and UIKit views to simplify the usage of the LottieRenderer-based rendering implementation, addressing the issue that consumers previously had to manually iterate through frames and create renderers themselves.

• Introduces a LottieViewModel that manages animation state and frame rendering
• Adds LottieView for SwiftUI integration with automatic animation lifecycle management
• Provides LottieUIKitView for UIKit integration with similar functionality

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
swift/Resources/test.json	Adds test Lottie animation data for development and preview
swift/LottieViewModel.swift	Core view model handling frame rendering, animation timing, and image conversion
swift/LottieView.swift	SwiftUI wrapper view with automatic animation start/stop on appear/disappear
swift/LottieUIKitView.swift	UIKit wrapper view providing similar functionality for UIKit contexts
swift/Lottie.swift	Adds getSize() method to retrieve animation dimensions
Package.swift	Updates package configuration to include Resources directory

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[Copilot]

There's a typo in the comment: 'propery' should be 'properly'.

Suggested change

	// TODO: Handle errors propery here.
	// TODO: Handle errors properly here.

[Copilot]

The error message 'Rendering error.' is too generic and doesn't provide useful debugging information. Consider including the actual error details or a more descriptive message.

Suggested change

	print(error)
	fatalError("Rendering error.")
	fatalError("Rendering error: \(error)")

[Copilot]

The error messages are inconsistent in style (all caps vs sentence case) and not descriptive. Consider using a consistent format and providing more context about what failed during the UIImage creation.

Suggested change

	print("UI IMAGE CAST ERROR")
	fatalError("UIImage cast error.")
	print("Failed to create UIImage from buffer. Buffer count: \(buffer.count), size: \(size), pixelFormat: .argb")
	fatalError("Failed to create UIImage from buffer with size \(size) and pixelFormat .argb.")

[Copilot]

The subscription to viewModel.$renderedFrame is created every time startAnimating() is called, but previous subscriptions are not cancelled. This will create multiple subscriptions and potential memory leaks. Consider cancelling existing subscriptions first or moving this subscription to setupView().