iOS模拟器运行颤振升级后性能不佳

升级颤振后，iOS模拟器的性能变得很差。例如，启动慢和显示键盘慢

我跑去看医生。这是我的结果

$ flutter doctor -v
[✓] Flutter (Channel master, v1.9.8-pre.35, on Mac OS X 10.14.6 18G87, locale ja-JP)
• Flutter version 1.9.8-pre.35 at /Users/rafekun/Developer/flutter
• Framework revision 1363528eee (4 days ago), 2019-08-31 05:26:41 -0400
• Engine revision cd858489cc
• Dart version 2.5.0 (build 2.5.0-dev.4.0 36985859e4)


[✓] Android toolchain - develop for Android devices (Android SDK         version 29.0.0)
• Android SDK at /Users/rafekun/Library/Android/sdk
• Android NDK location not configured (optional; useful for native profiling support)
• Platform android-29, build-tools 29.0.0
• Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
• Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b49-5587405)
• All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 10.3)
• Xcode at /Applications/Xcode.app/Contents/Developer
• Xcode 10.3, Build version 10G8
• CocoaPods version 1.7.5

[✓] Android Studio (version 3.5)
• Android Studio at /Applications/Android Studio.app/Contents
• Flutter plugin version 38.2.3
• Dart plugin version 191.8423
• Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b49-5587405)

[✓] VS Code (version 1.37.0)
• VS Code at /Applications/Visual Studio Code.app/Contents
• Flutter extension version 3.3.0

[✓] Connected device (1 available)
• iPhone Xʀ • B3C345C3-5AB0-4627-B854-2C90016A3B69 • ios •
  com.apple.CoreSimulator.SimRuntime.iOS-12-4 (simulator)

• No issues found!

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如果您在Xcode模拟器中的特定（较新）设备上运行缓慢、FPS低、滚动时间长，这是因为Apple放弃了对OpenGL的支持，而Flatter SDK在模拟器中不支持新的Metal API

但是官方的稳定支持很快就会提供，直到您需要60 FPS时，通过在终端中运行此命令切换到Flatter SDK的主通道并重建您的应用程序：

flutter channel master

资料来源：

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我将颤振SDK降级为更稳定的版本。但是，仍然存在相同的问题。附加

颤振运行-v

以获得更多诊断数据我找到了解决方案。只需取消选中模拟器中的“慢速动画”。Xcode模拟器和颤振SDK版本之间没有关系。