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/xamarin-ios-migration

@74acbe3
by David Ortinaudavidortinau/maui-skills173 stars
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**WORKFLOW SKILL** - Guide for migrating Xamarin.iOS, Xamarin.Mac, and Xamarin.tvOS native apps to .NET for iOS, .NET for macOS, and .NET for tvOS. Covers SDK-style project conversion, target framework monikers, MSBuild property changes, Info.plist updates, iOS binding library migration, Xamarin.Essentials in native apps, NuGet dependency compatibility, and code signing changes. USE FOR: "migrate Xamarin.iOS", "upgrade Xamarin.iOS to .NET", "Xamarin.iOS to .NET for iOS", "iOS project migration", "Xamarin.Mac migration", "tvOS migration", "iOS binding library migration", "MtouchArch to RuntimeIdentifier", "Apple project migration". DO NOT USE FOR: migrating Xamarin.Forms apps (use xamarin-forms-migration), migrating Xamarin.Android apps (use xamarin-android-migration), creating new MAUI apps from scratch (use feature-specific MAUI skills).

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Use this Skill: https://skilld.dev/gh/davidortinau/maui-skills/xamarin-ios-migration

This session only. Nothing lands on disk.

SKILL.md

≈218 tokens always: the name and description. ≈1.3k when used: this file. ≈1.5k more on demand in 1 file.

Xamarin.iOS / Xamarin.Mac / Xamarin.tvOS → .NET Migration

For SDK-style project templates, MSBuild property tables, RuntimeIdentifier conversion tables, and namespace mappings, see references/ios-migration-api.md.

Migration Workflow

  1. Create new .NET for iOS/macOS/tvOS project (same name, copy code into it)
  2. Update MSBuild properties (see references/ios-migration-api.md)
  3. Move MinimumOSVersion from Info.plist → SupportedOSPlatformVersion in csproj
  4. Copy code, resources, storyboards, entitlements
  5. Update NuGet dependencies
  6. Migrate binding libraries (if applicable)
  7. Replace Xamarin.Essentials with <UseMauiEssentials>true</UseMauiEssentials>
  8. Remove .dll.config files (not supported in .NET)
  9. Delete bin//obj/, build, verify code signing, test on device

Strategy: Create a new project and copy code into it — don't edit the existing project file.

Critical Gotchas

⚠️ No Backward Compatibility for iOS/Mac NuGet Packages

Unlike Android, there is no backward compatibility with old Xamarin iOS/Mac TFMs. Packages targeting monotouch, xamarinios, xamarinios10, monomac, or xamarinmac will not work — they must be recompiled for net8.0-ios etc.

⚠️ CodeSigningKey → CodesignKey Rename

<!-- ❌ Old property name — silently ignored -->
<CodeSigningKey>Apple Distribution: My Company</CodeSigningKey>

<!-- ✅ Renamed property -->
<CodesignKey>Apple Distribution: My Company</CodesignKey>

Also rename MtouchEnableSGenConc → EnableSGenConc.

⚠️ No .dll.config or .exe.config Support

.dll.config and <dllmap> are not supported in .NET Core. Migrate configuration to appsettings.json, embedded resources, or platform preferences.

⚠️ watchOS Is Not Supported

Xamarin.watchOS has no .NET equivalent. Bundle Swift extensions with .NET for iOS apps instead.

⚠️ OpenGL (iOS) Is Not Supported

OpenTK is unavailable in .NET for iOS. Migrate to Metal or SceneKit.

⚠️ Linker Behavior Is Stricter

Update LinkDescription XML files if custom linker configuration was used. The linker in .NET is stricter and may trim symbols that the Xamarin linker preserved.

Platform-Specific Pitfalls

Pitfall Impact Mitigation
iOS/Mac NuGet packages not backward-compatible Build failures for packages targeting xamarinios Recompile or find .NET-compatible alternatives
CodeSigningKey silently ignored App fails to sign but no clear error Rename to CodesignKey
MtouchArch not converted Wrong architecture targeted Convert to RuntimeIdentifier(s) — see reference tables
MinimumOSVersion left in Info.plist Ignored — uses csproj value Move to SupportedOSPlatformVersion
Entitlements path wrong Build succeeds but runtime failures Verify CodesignEntitlements points to correct file
.dll.config files present Silently ignored at runtime Remove and migrate to alternatives

Binding Library Migration Tips

  • Use SDK-style project format with net8.0-ios TFM
  • The binding generator and API definitions work the same way
  • Verify native frameworks are updated for the target iOS version
  • Test thoroughly — binding edge cases are common in .NET migrations

NuGet Compatibility Decision

Situation Action
You own the package Recompile with .NET TFMs
Package has preview .NET version Use preview
No compatible version Replace with .NET-compatible alternative
.NET Standard library (no platform deps) ✅ Still works

Build Troubleshooting

Issue Fix
Namespace not found Most UIKit namespaces are unchanged — verify against .NET for iOS API surface
Linker errors Update LinkDescription XML files — linker is stricter in .NET
Code signing failure Verify CodesignKey, CodesignProvision, CodesignEntitlements
Entitlements mismatch Ensure entitlements file matches provisioning profile

API Currency Warning

If your migrated app will also adopt .NET MAUI controls (e.g., via UseMaui), check the maui-current-apis skill for deprecated MAUI APIs to avoid (ListView, Frame, Device.*, etc.).

Quick Checklist

  1. ☐ Created new .NET for iOS/macOS/tvOS project
  2. ☐ Set TargetFramework to net8.0-ios (or -macos/-tvos)
  3. ☐ Moved MinimumOSVersion → SupportedOSPlatformVersion in csproj
  4. ☐ Converted MtouchArch → RuntimeIdentifier(s)
  5. ☐ Converted HttpClientHandler → UseNativeHttpHandler
  6. ☐ Renamed CodeSigningKey → CodesignKey
  7. ☐ Renamed MtouchEnableSGenConc → EnableSGenConc
  8. ☐ Copied source, resources, storyboards, entitlements
  9. ☐ Updated NuGet dependencies (no backward compat with Xamarin TFMs!)
  10. ☐ Added UseMauiEssentials + Platform.Init() if using Essentials
  11. ☐ Removed .dll.config files
  12. ☐ Deleted bin/ and obj/ folders
  13. ☐ Verified code signing and provisioning
  14. ☐ Tested on physical device

Source: SKILL.md on GitHub

Third-party checks

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  • Gen Agent Trust Hub15d

    The skill provides technical documentation, migration workflows, and project templates for upgrading Xamarin.iOS, Xamarin.Mac, and Xamarin.tvOS applications to .NET. It contains MSBuild property mapping tables and standard C# initialization code. No security issues or malicious patterns were detected.

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    Risk: LOW · No issues

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Provenance

Signed by skilld at 74acbe3. This ties the file your Agent reads to that commit on GitHub. It does not review the instructions.

Last checked against GitHub 2 months ago.

Steadyupdated 6 months ago

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