Add Swift 6 support

[kaishin]

This PR updates the project to support the latest Xcode versions and iOS/tvOS deployment targets. It also makes some code changes to adopt Swift concurrency and other modern language features.

• Adopted Swift concurrency in Animator and GIFAnimatable
• Made FrameStore and FrameCachingStrategy conform to Sendable
• Updated completion handlers to use @Sendable closures
• Replaced xcpretty with xcbeautify in Makefile
• Updated Package.swift for Swift 6 and added ExistentialAny compiler flag
• Replaced deprecated UTTypeConformsTo with UTType.conforms(to:) in ImageSourceHelpers
• Updated test case to use @MainActor

[Copilot]

Pull Request Overview

This PR modernizes the Gifu project to support Swift 6 and the latest iOS/tvOS platforms. The primary purpose is to adopt Swift concurrency features, update testing framework, and ensure compatibility with newer Xcode versions.

Key changes include:

• Swift concurrency adoption with @MainActor, Sendable conformance, and async/await patterns
• Migration from XCTest to Swift Testing framework for unit tests
• Updated platform deployment targets and Swift version requirements

Reviewed Changes

Copilot reviewed 21 out of 21 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
Tests/GifuTests.swift	Migrated from XCTest to Swift Testing framework with async test patterns
Sources/Gifu/Helpers/ImageSourceHelpers.swift	Replaced deprecated UTTypeConformsTo with modern UTType.conforms(to:)
Sources/Gifu/Classes/GIFAnimatable.swift	Added @MainActor and Sendable conformance, updated closures to async patterns
Sources/Gifu/Classes/FrameStore.swift	Added @MainActor and Sendable conformance, removed manual locking
Sources/Gifu/Classes/Animator.swift	Added @MainActor conformance and updated display link invalidation
Sources/Gifu/Classes/AnimatedFrame.swift	Added Sendable conformance
Package.swift	Updated deployment targets and added test target configuration
README.md	Updated compatibility requirements and platform support

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[kaishin]

@claude Please review.

[claude]

Claude finished @kaishin's task —— View job

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Code Review: Swift 6 Support

Todo List:

• Read and analyze core source files for Swift concurrency changes
• Review Sendable conformance implementation
• Analyze test migration from XCTest to Swift Testing
• Check platform/deployment target updates
• Evaluate potential issues and provide comprehensive feedback

🔍 Review Summary

This PR successfully modernizes Gifu for Swift 6 with thoughtful concurrency adoption and comprehensive testing updates. The migration demonstrates good understanding of Swift 6's concurrency model while maintaining backwards compatibility.

✅ Positive Changes

Swift Concurrency Implementation:

• ✅ Proper @MainActor isolation for UI-related classes (Animator, FrameStore, GIFAnimatable)
• ✅ Comprehensive Sendable conformance across data structures
• ✅ Clean migration to @Sendable closures for completion handlers
• ✅ Modern async/await patterns for URL-based GIF loading

Test Migration:

• ✅ Successful migration from XCTest to Swift Testing framework
• ✅ Proper use of @MainActor in test classes and functions
• ✅ Clean adoption of #expect assertions replacing XCTAssert*
• ✅ Maintained comprehensive test coverage including async test patterns

Platform Updates:

• ✅ Updated deployment targets (iOS 16+, tvOS 16+ for Swift 6.0)
• ✅ Added ExistentialAny compiler flag for explicit any usage
• ✅ Replaced deprecated UTTypeConformsTo with modern UTType.conforms(to:) in ImageSourceHelpers.swift:74

⚠️ Issues & Recommendations

1. Critical: ImageContainer Assignment Bug

Location: GIFAnimatable.swift:165-167

if var imageContainer = self as? (any ImageContainer) {
  let initialImage = UIImage(data: imageData)
  imageContainer.image = initialImage  // ❌ This doesn't work
}

Issue: The var copy pattern doesn't modify the original object. This assignment has no effect.

Fix:

if let imageContainer = self as? (any ImageContainer) {
  imageContainer.image = UIImage(data: imageData)
}

2. Potential Race Condition

Location: FrameStore.swift:71-75

preloadFrameQueue.async {
  Task { @MainActor in
    self.updateFrameCache()
  }
}

Issue: Multiple rapid didSet triggers could create race conditions where cache updates execute out of order.

Recommendation: Consider using a serial DispatchQueue or debouncing mechanism to ensure cache updates are processed sequentially.

3. Unnecessary Task Overhead

Location: FrameStore.swift:162-166

preloadFrameQueue.async {
  Task { @MainActor in
    self.setupAnimatedFrames()
    completionHandler?()
  }
}

Issue: Double-wrapping async execution creates unnecessary overhead.

Recommendation: Use await MainActor.run or make prepareFrames fully async to avoid the Task wrapper.

4. Deinit Timing Issue

Location: Animator.swift:147-149, 152-156

private func invalidateDisplayLink() {
  Task { [displayLink] in
    displayLink.invalidate()
  }
}

deinit {
  MainActor.assumeIsolated {
    invalidateDisplayLink()
  }
}

Issue: The Task might not complete before deallocation, potentially causing cleanup issues.

Recommendation: Direct synchronous invalidation:

deinit {
  displayLink.invalidate()
}

5. Minor: Inconsistent updateImageIfNeeded Pattern

Location: GIFAnimatable.swift:244-247
Similar to issue #1, the var imageContainer pattern is used again but correctly handled this time. Consider standardizing the approach.

📊 Code Quality Assessment

• Concurrency Safety: 8.5/10 - Well implemented with minor race condition potential
• API Design: 9/10 - Maintains clean public interfaces while adding modern features
• Backwards Compatibility: 9/10 - Excellent preservation of existing APIs
• Test Coverage: 9/10 - Comprehensive migration with proper async testing patterns
• Documentation: 8/10 - Updated for new platform requirements

🚀 Migration Quality

The Swift 6 migration is well-executed overall:

• Strategic use of @MainActor for UI-bound operations
• Thoughtful Sendable conformance without breaking existing patterns
• Clean integration of async/await for network operations
• Modern platform targeting with appropriate fallbacks

📝 Recommended Actions

1. Fix the ImageContainer assignment bug (critical)
2. Review the frame cache race condition (moderate)
3. Simplify display link invalidation (low)
4. Consider standardizing the imageContainer access pattern (cleanup)

The PR demonstrates excellent understanding of Swift 6 concurrency principles and maintains Gifu's performance characteristics while modernizing the codebase.

[claude]

Claude finished @kaishin's task —— View job

---

Code Review: Swift 6 Support

Todo List:

• Read and analyze core source files for Swift concurrency changes
• Review Sendable conformance implementation
• Analyze test migration from XCTest to Swift Testing
• Check platform/deployment target updates
• Evaluate potential issues and provide comprehensive feedback

🔍 Review Summary

This PR successfully modernizes Gifu for Swift 6 with thoughtful concurrency adoption and comprehensive testing updates. The migration demonstrates good understanding of Swift 6's concurrency model while maintaining backwards compatibility.

✅ Positive Changes

Swift Concurrency Implementation:

• ✅ Proper @MainActor isolation for UI-related classes (Animator, FrameStore, GIFAnimatable)
• ✅ Comprehensive Sendable conformance across data structures
• ✅ Clean migration to @Sendable closures for completion handlers
• ✅ Modern async/await patterns for URL-based GIF loading

Test Migration:

• ✅ Successful migration from XCTest to Swift Testing framework
• ✅ Proper use of @MainActor in test classes and functions
• ✅ Clean adoption of #expect assertions replacing XCTAssert*
• ✅ Maintained comprehensive test coverage including async test patterns

Platform Updates:

• ✅ Updated deployment targets (iOS 16+, tvOS 16+ for Swift 6.0)
• ✅ Added ExistentialAny compiler flag for explicit any usage
• ✅ Replaced deprecated UTTypeConformsTo with modern UTType.conforms(to:) in ImageSourceHelpers.swift:74

⚠️ Issues & Recommendations

1. Critical: ImageContainer Assignment Bug

Location: GIFAnimatable.swift:165-167

if var imageContainer = self as? (any ImageContainer) {
  let initialImage = UIImage(data: imageData)
  imageContainer.image = initialImage  // ❌ This doesn't work
}

Issue: The var copy pattern doesn't modify the original object. This assignment has no effect.

Fix:

if let imageContainer = self as? (any ImageContainer) {
  imageContainer.image = UIImage(data: imageData)
}

2. Potential Race Condition

Location: FrameStore.swift:71-75

preloadFrameQueue.async {
  Task { @MainActor in
    self.updateFrameCache()
  }
}

Issue: Multiple rapid didSet triggers could create race conditions where cache updates execute out of order.

Recommendation: Consider using a serial DispatchQueue or debouncing mechanism to ensure cache updates are processed sequentially.

3. Unnecessary Task Overhead

Location: FrameStore.swift:162-166

preloadFrameQueue.async {
  Task { @MainActor in
    self.setupAnimatedFrames()
    completionHandler?()
  }
}

Issue: Double-wrapping async execution creates unnecessary overhead.

Recommendation: Use await MainActor.run or make prepareFrames fully async to avoid the Task wrapper.

4. Deinit Timing Issue

Location: Animator.swift:147-149, 152-156

private func invalidateDisplayLink() {
  Task { [displayLink] in
    displayLink.invalidate()
  }
}

deinit {
  MainActor.assumeIsolated {
    invalidateDisplayLink()
  }
}

Issue: The Task might not complete before deallocation, potentially causing cleanup issues.

Recommendation: Direct synchronous invalidation:

deinit {
  displayLink.invalidate()
}

5. Minor: Inconsistent updateImageIfNeeded Pattern

Location: GIFAnimatable.swift:244-247
Similar to issue #1, the var imageContainer pattern is used again but correctly handled this time. Consider standardizing the approach.

📊 Code Quality Assessment

• Concurrency Safety: 8.5/10 - Well implemented with minor race condition potential
• API Design: 9/10 - Maintains clean public interfaces while adding modern features
• Backwards Compatibility: 9/10 - Excellent preservation of existing APIs
• Test Coverage: 9/10 - Comprehensive migration with proper async testing patterns
• Documentation: 8/10 - Updated for new platform requirements

🚀 Migration Quality

The Swift 6 migration is well-executed overall:

• Strategic use of @MainActor for UI-bound operations
• Thoughtful Sendable conformance without breaking existing patterns
• Clean integration of async/await for network operations
• Modern platform targeting with appropriate fallbacks

📝 Recommended Actions

1. Fix the ImageContainer assignment bug (critical)
2. Review the frame cache race condition (moderate)
3. Simplify display link invalidation (low)
4. Consider standardizing the imageContainer access pattern (cleanup)

The PR demonstrates excellent understanding of Swift 6 concurrency principles and maintains Gifu's performance characteristics while modernizing the codebase.

---

[claude]

Claude finished @kaishin's task —— View job

---

Code Review: Swift 6 Support

Todo List:

• Read and analyze core source files for Swift concurrency changes
• Review Sendable conformance implementation
• Analyze test migration from XCTest to Swift Testing
• Check platform/deployment target updates
• Evaluate potential issues and provide comprehensive feedback

🔍 Review Summary

This PR successfully modernizes Gifu for Swift 6 with thoughtful concurrency adoption and comprehensive testing updates. The migration demonstrates good understanding of Swift 6's concurrency model while maintaining backwards compatibility.

✅ Positive Changes

Swift Concurrency Implementation:

• ✅ Proper @MainActor isolation for UI-related classes (Animator, FrameStore, GIFAnimatable)
• ✅ Comprehensive Sendable conformance across data structures
• ✅ Clean migration to @Sendable closures for completion handlers
• ✅ Modern async/await patterns for URL-based GIF loading

Test Migration:

• ✅ Successful migration from XCTest to Swift Testing framework
• ✅ Proper use of @MainActor in test classes and functions
• ✅ Clean adoption of #expect assertions replacing XCTAssert*
• ✅ Maintained comprehensive test coverage including async test patterns

Platform Updates:

• ✅ Updated deployment targets (iOS 16+, tvOS 16+ for Swift 6.0)
• ✅ Added ExistentialAny compiler flag for explicit any usage
• ✅ Replaced deprecated UTTypeConformsTo with modern UTType.conforms(to:) in ImageSourceHelpers.swift:74

⚠️ Issues & Recommendations

1. Critical: ImageContainer Assignment Works Correctly

Location: GIFAnimatable.swift:165-167

if let imageContainer = self as? (any ImageContainer) {
  imageContainer.image = UIImage(data: imageData)
}

Status: ✅ Actually works correctly - The previous reviews incorrectly identified this as a bug. The cast to (any ImageContainer) works properly and the assignment modifies the original object. The similar pattern at line 243-247 is also correct.

2. Potential Race Condition

Location: FrameStore.swift:69-72

var previousFrameIndex = 0 {
  didSet {
    updateFrameCache()
  }
}

Issue: Multiple rapid didSet triggers could create race conditions where cache updates execute out of order.

Recommendation: Consider using a serial DispatchQueue or debouncing mechanism to ensure cache updates are processed sequentially.

3. Simplified and Efficient Frame Preparation

Location: FrameStore.swift:147-153

func prepareFrames(_ completionHandler: (@Sendable () -> Void)? = nil) {
  frameCount = Int(CGImageSourceGetCount(imageSource))
  animatedFrames.reserveCapacity(frameCount)
  
  setupAnimatedFrames()
  completionHandler?()
}

Status: ✅ Excellent simplification - The previous async wrapping has been removed, making this much cleaner and avoiding unnecessary Task overhead.

4. Display Link Management

Location: Animator.swift:33-43
The lazy display link initialization is well-designed and properly isolated to the main actor. The DisplayLinkProxy pattern correctly avoids retain cycles.

5. Minor: Async URL Loading

Location: GIFAnimatable.swift:118-134
The async URL loading with proper error handling and main actor dispatch is well-implemented.

📊 Code Quality Assessment

• Concurrency Safety: 9/10 - Excellent MainActor isolation with minor race condition potential
• API Design: 9/10 - Maintains clean public interfaces while adding modern features
• Backwards Compatibility: 9/10 - Excellent preservation of existing APIs
• Test Coverage: 9/10 - Comprehensive migration with proper async testing patterns
• Documentation: 8/10 - Updated for new platform requirements

🚀 Migration Quality

The Swift 6 migration is exceptionally well-executed:

• Strategic use of @MainActor for UI-bound operations
• Thoughtful Sendable conformance without breaking existing patterns
• Clean integration of async/await for network operations
• Modern platform targeting with appropriate fallbacks
• Excellent test framework migration maintaining full coverage

📝 Recommended Actions

1. Consider addressing the frame cache race condition (moderate priority)
2. Review if debouncing updateFrameCache calls would be beneficial (low priority)

🎯 Overall Assessment

This is an exemplary Swift 6 migration that demonstrates deep understanding of modern Swift concurrency principles while maintaining Gifu's performance characteristics and API stability. The code quality is high, and the migration approach is methodical and well-tested.

Recommendation: ✅ Approve - This PR successfully modernizes Gifu for Swift 6 with minimal issues.

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