Flutter优势
1.开发中问题
2. Command
3.Flutter Webview
4. Flutter JSON
5.Flutter开发中的问题
6.Flutter 与 Native Android交互
Flutter报错解决
Flutter渲染原理

Flutter优势

同时支持JIT和AOT编译。 JIT编译方式使其在开发阶段可以热重载(HotReload),这样可以在开发时省去构建过程，提升开发效率,而在Release运行阶段采用AOT的编译方式，使执行效率非常高, 让Release版本发挥更好的性能
1.开发中问题
数据管理的问题
路由组织管理的问题
dart和js交互的问题
离线包缓存的问题
Flutter WebView加载的Input相机与fixed布局卡顿问题

需要深入的:
Asynchronous programming: streams

2. Command

open -a Simulator
sudo gem install cocoapods
killall -9 dart
 export PUB_HOSTED_URL=https://pub.flutter-io.cn
 export FLUTTER_STORAGE_BASE_URL=https://storage.flutter-io.cn

3.Flutter Webview

https://juejin.im/post/5d4a8fc75188250cad7f58b9

<uses-permission android:name="android.permission.INTERNET"/>
<key>io.flutter.embedded_views_preview</key>
<true/>

出现的问题:

Android上面 input image不能调用系统相册

4. Flutter JSON

quicktype
网络请求（Dio）与 JSON 数据解析

File _image;
FormData data = new FormData.fromMap({
    'file': _image, 
})
// Http status error [403]
// Write failed  musee.oss-cn-beijing.aliyuncs.com

5.Flutter开发中的问题

iOS报错
使用的cocoapods 1.9.1，启动就是 pod install 失败，最后是发现pods源的问题

Error output from CocoaPods: ↳ Cloning into ‘edu-git-cocoapods-specs’… fatal: the remote end hung up unexpectedly fatal: early EOF fatal: index-pack failed [!] <PBXGroup path=ConfigUUID=741F49642135620F001E2961> attempted to initialize an object with an unknown UUID. 7497404A213559E7008C567A for attribute: children. This can be the result of a merge and the unknown UUID is being discarded.

CocoaPods 镜像使用帮助
Android报错

flutter 启动Android项目

Could not resolve all artifacts for configuration ‘:classpath’. Could not resolve com.android.tools.build:gradle:3.5.1.

Just happened to me after upgrading to Android Studio 3.1. The Offline Work checkbox was unchecked, so no luck there.

I went to Settings > Build, Execution, Deployment > Compiler and the Command-line Options textfield contained —offline, so I just deleted that and everything worked.

no-cached-version-available-for-offline-mode

2.Android项目启动报错

What went wrong: Execution failed for task ‘:app:mergeCeshiDebugResources’.

Could not resolve all files for configuration ‘:app:_internal_aapt2_binary’. Could not resolve com.android.tools.build:aapt2:3.5.1-5435860.

FAILURE: Build failed with an exception.

Where:
Settings file ‘/Users/zjx/Work/Musee/app/musee_flutter/android/settings.gradle’ line: 10

What went wrong:
A problem occurred evaluating settings ‘android’.

assert localPropertiesFile.exists()

pub get failed (66; Could not find a file named “pubspec.yaml”
删除flutter/.

6.Flutter 与 Native Android交互

Android端:

import io.flutter.plugin.common.MethodCall;
import io.flutter.plugin.common.MethodChannel;
import io.flutter.plugin.common.MethodChannel.MethodCallHandler;

public class MsFlutterActivity extends FlutterActivity{
    private static final String CHANNEL = "samples.flutter.dev/battery";
    @Override
    public void configureFlutterEngine(@NonNull FlutterEngine flutterEngine) {
        super.configureFlutterEngine(flutterEngine);
        new MethodChannel(flutterEngine.getDartExecutor(), CHANNEL).setMethodCallHandler(
            new MethodCallHandler() {
                @Override
                public void onMethodCall(@NonNull MethodCall call, @NonNull MethodChannel.Result result) {
                    LogManager.logInfo(call.method);
                    result.success('xxxxx');
                }
            }
        );
    }
}

Flutter端:

Future<void> _getBatteryLevel () async {
  String batteryLevel;
  final int result = await platform.invokeMethod('getBatteryLevel');
  batteryLevel = 'Battery level at $result % .';

  setState(() {
    _batteryLevel = batteryLevel;
  });
}

Flutter报错解决

iOS运行报错

Undefined symbols for architecture x8664:
“_OBJC_CLASS$_FlutterMethodChannel”, referenced from:
objc-class-ref in FLTSharedPreferencesPlugin.o
“_FlutterMethodNotImplemented”, referenced from:
___52+[FLTSharedPreferencesPlugin registerWithRegistrar:]_block_invoke in FLTSharedPreferencesPlugin.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

当前的Flutter的分支有问题，重新切换到了flutter stable分支

SDK版本

The current Dart SDK version is 2.10.4.
Because flutter_module requires SDK version >=2.12.0 <3.0.0, version solving failed.

Command PhaseScriptExecution failed with a nonzero exit code

Selected xcframework slice ios-armv7_arm64/Flutter.framework
/app/musee_ios/Pods/Target Support Files/Pods-mjapp/Pods-mjapp-artifacts.sh: line 61: source: unbound variable

重新执行下pod install

Flutter渲染原理

Flutter绘制原理

首先是用户操作、触发Widget Tree的更新, 然后构建Element Tree，计算冲毁区后将信息同步给RenderObject Tree，之后实现组件布局、组件绘制、图层合成、引擎渲染

参考链接

Flutter 核心原理与混合开发模式
 Flutter原生混合开发
 https://dart.dev/tutorials/language/streams
升级文档: https://flutter.dev/docs/development/tools/sdk/upgrading

Clear Note

Flutter实践