Xamarin.iOS 11.8 Release Notes

System Requirements | What's New | Known Issues | Blogs | Open Source



  • The latest features and API requires Xcode 9.2 and the bundled iOS, tvOS and watchOS SDKs;
  • Apple Xcode 9.2 requires a Mac running OSX 10.12.6 (Sierra) or newer;


Your feedback is important to us. If there are any problems with this release, check the Xamarin.iOS Forums and GitHub Issues for existing issues. If you do not find any matching issue, please feel free to start a new discussion and report an issue.

Release History

This version Xamarin.iOS correspond to our 15.6 (d15-6) milestone.

  • March 26, 2018 - Xamarin.iOS
  • February 23, 2018 - Xamarin.iOS
  • February 7, 2018 - Xamarin.iOS
  • January 24, 2018 - Xamarin.iOS
  • January 10, 2018 - Xamarin.iOS

You can learn more about how we ship our releases in the Visual Studio 2017 Release Rhythm document.

March 26, 2018 - Xamarin.iOS

This version is included in the Visual Studio 2017 version 15.6 Service Release 3.

Issues Fixed

  • 3289 - [msbuild] "dyld: Library not loaded: @rpath/Mono.framework/Mono" when debugging tvOS
  • 7472 - [runtime] NullReferenceException when trying to use an extension method on a null object as an assignment value for an Action or Func variable

February 23, 2018 - Xamarin.iOS

This version is included in the Visual Studio 2017 version 15.6 RTW release.

Issue Fixed

  • 3241 - [llvm] Revert "[mini] Align stack when resuming to catch handler"

February 7, 2018 - Xamarin.iOS

This version is included in the Visual Studio 2017 version 15.6 Preview 4 release.

Issues Fixed

  • 3089 - [coregraphics] Fix CGPath.MakeMutable reference count
  • 3215 - [linker] Fix general MT2001 to report a useful MT2002 error
  • 3241 - [mono] Fix runtime crash in armv7/llvm builds

January 24, 2018 - Xamarin.iOS

This version is included in the Visual Studio 2017 version 15.6 Preview 3 release.

Issues Fixed

  • 3140 - [vision] Removes incorrect [Abstract] from VNDetectBarcodesRequest
  • 3145 - [scenekit] Crashes if SCNAnimation.AnimationEvents isn't empty
  • 3146 - [scenekit] SCNPhysicsWorld.ConvexSweepTest method doesn't work
  • 6428 - [bcl] DnsCallback as async callback causing unhandled exception
  • 52729 - [msbuild] Xamarin.Mac and Xamarin.iOS load mismatched assemblies in one build process

January 10, 2018 - Xamarin.iOS

This version is included in the Visual Studio 2017 version 15.6 Preview 2 release.

Issues Fixed

  • 32022 - [foundation] Fix DateTime from NSDate seconds (decimal) precision loss when converting
  • 37527 - [generator] Incorrect BI1029 Internal error reported (instead of BI1113)
  • 58227 - [photos] Fix incorrect SDPHLivePhotoFrameProcessingBlock signature
  • 58544 - [msbuild] Set the target architecture in the Info.plist UIRequiredDeviceCapabilities
  • 58792 - [generator] Disallow the use of [Async] when the signature contains ref/out parameters
  • 59196 - [uikit] UIAccessibility.RequestGuidedAccessSession completion handler is an ObjC block
  • 59379 - [msbuild] Codesign iOS Simulator builds using the '-' key. Fix 'App Groups' support on simulator for iOS11
  • 59547 - [metalperformanceshaders] Premature collection possible in some bindings
  • 59617 - [registrar] Fix static registrar to detect invalid type usage
  • 59697 - [msbuild] Don't run Xamarin.Analysis on library projects
  • 59756 - [msbuild] Force-Init AppleSdkSettings in DetectSdkLocationsTaskBase
  • 59798 - [mtouch] Show MT0123 if the executable assembly does not reference the product assembly
  • 59848 - [msbuild] Fixed ObjC binding targets to delete target zip files before re-zipping
  • 59911 - [audiotoolbox] Free the right GCHandle when failing to create an InputAudioQueue
  • 59928 - [storekit] Fix SKCloudServiceSetupOptions strong dictionary's Action
  • 59947 - [llvm][bitcode] Attempting to JIT compile method 'ExceptionTests:test_1_basic_filter_catch ()' while running in aot-only mode.
  • 59994 - [runtime] Don't hold the framework lock when running managed code
  • 60176 - [linker] Handle ParameterInfo preserved from XML definitions
  • 60303 - [homekit] Expose weakly-typed API since the constants are extensible
  • 60377 - [msbuild] Fix possible confusion by similar provisioning profiles
  • 60423 - [security] Add RequestSharedWebCredential overload fixing [__NSCFDictionary UTF8String]: unrecognized selector sent to instance
  • 60536 - [msbuild] Catch json parser exceptions to provide better error reporting
  • 60545 - [mono] Multiple argument generic with contravariant interface as an argument causes MissingMethodException
  • 60771 - [aot] Attempting to JIT compile method 'System.Runtime.CompilerServices.Unsafe:Add (byte&,int)' while running in aot-only mode
  • 61039 - [mtouch] Fix Xamarin.Sdk.framework not to link with private frameworks when trying to support older OS where they were not yet available
  • 61056 - [arkit] Fix Vertices, 'TextureCoordinates' and 'TriangleIndices' types in ARFaceGeometry
  • 3089 - [coreanimation] Ensure that we increase the handle reference count in MakeMutable

Breaking Changes

  • 59572 - [msbuild] Emit a build error when CFBundleIdentifier is null or empty


  • 52570 - [generator] warn when [Static] is used in a [Category]
  • 53076 - [generator] Lack of error when [Async] is used inside a type decorated with [Protocol]
  • 57094 - [generator] Improve BI1014 to include the name of unsupported field and valid types
  • 57795 - [generator] Allow [BindAs] attribute for smart enum used in multidimensional arrays
  • 57797 - [generator] Support [BindAs] attribute for smart enums of an array of nullable types
  • 57804 - [generator] Slightly incorrect error message when trying to use ref/out parameters with [BindAs] attributes
  • 58251 - [msbuild] Add support for optionally explaining why inapplicable certificates are not applicable
  • 59278 - [security] Add missing item in SecStatusCode enum
  • 59296 - [coreimage] Some kCI*keys are missing
  • 59537 - [coreanimation] CATextLayer.Alignment* strings should be CATextLayerAlignment enum
  • 60280 - [mtouch][mmp] Allow the use of major-only version numbers in arguments
  • 60537 - [localauthentication] LABiometryType.TypeFaceId enum name is not consistent
  • 60541 - [foundation] Expose initWithDictionary:copyItems: in NS[Mutable]Array

Integrated Mono Features/Fixes

Xamarin.iOS uses a customized runtime and base class libraries (BCL) from Mono 5.11 (hash).

Additional information can be found in Mono release notes.

What's New in this Release

This release is built upon our open sourced SDK and offers the following new features:

Support for wireless deployment and debugging

The new Apple TV 4K (5th generation) does not have an USB (C) connector, which is the usual way for developers to install and debug applications on devices.

Xamarin.iOS now has the capability to detect devices connected via network (Wi-Fi or Ethernet) and in combination with our latest Visual Studio for Mac release (Version 7.4 Preview 2) debugging over network is also possible.

Please take a look at the Visual Studio for Mac release notes for more details.

Base Class Libraries (BCL) Debugging

Developers can now step into the Base Class Libraries code as well as the Xamarin SDK source code while debugging their application. In order to be able to step into the BCL and Xamarin SDK in a project the following has to be configured:

Visual Studio for Mac

  • Un-check the "Debug code project only; do not step into framework code" option via the Preferences > Debugger menu.

Visual Studio

  • Un-check the "Enable Just My Code" option via the Tools > Options > Debugging menu.

For iOS Simulator builds, the above steps are all that is required. To debug BCL or Xamarin SDK source on a device, add the --debug:all flag as an extra mtouch argument. Open the Project > Properties ("Options" in Visual Studio for Mac) menu. New flags can be added to mtouch in the "iOS Build" panel via the textbox labeled "Additional mtouch arguments:". This flag should only be set when debugging is required and should be removed for production applications since it will greatly increase the size of the application.

mtouch support for response file

The mtouch tool has a new option that accept arguments inside a response file.

  • 56501 - MSB6002 command-line for MTouch task is too long, > 32000 characters / [mtouch/mmp/bgen] Add support for response files. (#2808)

The mentioned limit is for Windows and the default one for macOS is quite larger.

Xamarin.Analysis HttpClient handler rule

We added a new rule to our project analysis tool which recommends using a native HttpClientHandler instead of the managed one for better performance, smaller executable size, and to easily support the newer standards.

As a reminder to run the rules, in Visual Studio for Mac's menu, select Project > Run Code Analysis.

Note: all existing rules are documented here.

Known Issues

Using an older Xcode version

Using an older Xcode version (than the one mentioned in the above requirements) is often possible, but some features may not be available. Also some limitations might requires workarounds, e.g.:

  • The static registrar requires Xcode headers files to build applications, leading to MT0091 or MT4109 errors if API are missing. In most cases enabling the managed linker will help (by removing the API).
  • Bitcode builds (for tvOS and watchOS) can fail submission to the App Store unless an Xcode 9.0+ toolchain is used.

Open Source

Xamarin.iOS is based on the following open-source repositories: