iOS Photo Editing SDK Build

I want to package a lightweight, well-documented photo-editing SDK for iOS that my team can drop straight into our existing Swift app. The only feature set I need for the first release is a robust “Filters & Effects” module, and within that, artistic filters are non-negotiable—think sketch, watercolor, cartoon, and similar creative looks.

Core expectations
• Written natively for iOS (Swift preferred; Objective-C compatibility via bridging is a plus).
• Clean, public API delivering real-time previews, intensity sliders, and GPU-accelerated processing.
• Modular structure so additional tools (crop, text, etc.) can be bolted on later without refactoring.
• Comprehensive developer docs and inline code comments.
• A small demo app that showcases every artistic filter and illustrates best-practice integration.
• Unit tests covering filter accuracy and performance.

Acceptance will be based on compiling the SDK into our sandbox project, running the demo, and verifying that each artistic filter renders within the target frame rate on an iPhone 12. If you have prior experience with Core Image, Metal, or third-party GPU frameworks, mention it so I can gauge fit quickly.