Cross-Platform: macOS ↔ iOS

Patterns for sharing code between macOS and iOS, building iOS-specific extensions, and syncing data across platforms.

Critical Constraints

• ❌ Never import AppKit or UIKit in shared code — use SwiftUI types and #if os() for platform-specific imports
• ❌ Never use NSColor/UIColor directly in shared views — use SwiftUI Color
• ❌ Never use NSFont/UIFont directly — use SwiftUI .font()
• ✅ Abstract platform services behind protocols
• ✅ Use #if os(macOS) / #if os(iOS) for platform-specific implementations
• ✅ Use @Environment(\.horizontalSizeClass) for adaptive layouts within a platform

Project Structure