Doctor summary (to see all details, run flutter doctor -v):

[?] Flutter (Channel stable, v1.2.1, on Mac OS X 10.13.6 17G65, locale zh-Hans-CN)

[!] Android toolchain - develop for Android devices (Android SDK version 28.0.0-rc2)

? ? ? Flutter requires Android SDK 28 and the Android BuildTools 28.0.3

? ? ? To update using sdkmanager, run:

? ? ? ? /Users/yanjing/Library/Android/sdk/tools/bin/sdkmanager "platforms;android-28" "build-tools;28.0.3"

? ? ? or visit https://flutter.io/setup/#android-setup for detailed instructions.

[?] iOS toolchain - develop for iOS devices (Xcode 10.1)

[?] Android Studio (version 3.1)

[?] VS Code (version 1.30.1)

[?] Connected device (2 available)

! Doctor found issues in 1 category.

按照 提示 操作 ok

yanjingdeMacBook-Pro:Flutter yanjing$ flutter doctor

Doctor summary (to see all details, run flutter doctor -v):

[?] Flutter (Channel stable, v1.2.1, on Mac OS X 10.13.6 17G65, locale zh-Hans-CN)

[?] Android toolchain - develop for Android devices (Android SDK version 28.0.3)

[?] iOS toolchain - develop for iOS devices (Xcode 10.1)

[?] Android Studio (version 3.1)

[?] VS Code (version 1.30.1)

[?] Connected device (2 available)