iOS模拟器运行flutter升级后性能不佳

Question

升级flutter后，iOS模拟器的性能变得如此糟糕。例如，启动慢，显示键盘慢。

我查了颤振医生。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!

Answer 1

如果你在Xcode模拟器中的特定（较新）设备上遇到缓慢、低FPS和滞后的滚动，那是因为苹果放弃了对OpenGL的支持，而Flutter SDK不支持模拟器中的新金属API。

但是官方的稳定支持将很快可用，直到如果你需要60个FPS，通过在终端中运行这个切换到Flutter SDK的主通道，并重建你的应用程序：

flutter channel master

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