打包app时遇到了如下错误提示，使用的是xcode9.2

Invalid Toolchain. Your app was built with an unsupported version of Xcode or SDK. If you plan to submit this build to the App Store, make sure you are using the GM version of Xcode 9 and the SDK for iOS 11, tvOS 11, watchOS 4, or macOS 10.13 or later. If you are using an Xcode beta version to test your app, make sure you are using the latest supported version. For more information about supported beta versions, view the TestFlight Release Notes (https://developer.apple.com/testflight/release-notes/).