Please see https://releases.xamarin.com/preview-xcode-9-1-beta-2-ios-11-1-support-preview-1 for the details about this release, including installation instructions and links to the downloads and release notes.
These are preview builds to allow Xamarin developers to start trying the new features available from Apple in Xcode 9.1 beta 2. Any bug reports about the new Xamarin bindings are much appreciated!
File a bug report against Xamarin.iOS 11.3 if you see any problematic behavior in this preview Xamarin.iOS version that you wish to report.
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