简单地说：Flutter 是一个移动 SDK ，可以创建混合移动应用（编写一份代码，在 Android 和 iOS 都可以运行这个应用程序）。
学习地址 Flutter中文网：https://flutterchina.club/
本人开始入坑flutter,使用mac系统进行安装，遇到了一些坑，记录一下，并简单总结一下步骤。
1.首先为什么要用 Flutter ？
1.1 应用运行期间使用热重载改变 UI
1.2 非常丰富的内置 UI 组件
1.3 UI 非常简单—— 所有东西都是一个小部件
1.4 兼容Android / iOS 差异化主题
1.5 谷歌亲儿子-社区活跃（http://flutter-dev.cn/）、资源丰富（https://pub.dartlang.org/flutter）
2.安装Flutter SDK
2.1下载地址：https://flutter.io/sdk-archive/#macos
（ps:昨天下载的v0.8.6,今天就更新到0.9.1）
2.2 解压到你电脑某个文件夹下 ，如：
cd ~/development
unzip ~/Downloads/flutter_macos_v0.8.6-dev.zip
解压完成
3.配置环境变量
export PUB_HOSTED_URL=https://pub.flutter-io.cn
export FLUTTER_STORAGE_BASE_URL=https://storage.flutter-io.cn
export PATH=`pwd`/flutter/bin:$PATH
export PATH=/Users/yingyou/Documents/flutter/bin:$PATH
export ANDROID_HOME=/Users/yingyou/Documents/android/sdk
export PATH=${PATH}:${ANDROID_HOME}/tools
export PATH=${PATH}:${ANDROID_HOME}/platform-tools
export PUB_HOSTED_URL=https://pub.flutter-io.cn
export FLUTTER_STORAGE_BASE_URL=https://storage.flutter-io.cn
终端配置方法：
env //查看环境变量
cd ~ && ls -a && sudo vim .bashrc //修改环境变量，输入上面的环境变量
//输完后依次按 'esc' => ':wq'
source ~/.bashrc //配置生效 //在终端再输入env查看是否成功
flutter doctor //命令查看是否需要安装其它依赖项来完成安装
坑：-bash: flutter: command not found
1.检查ANDROID_HOME的值路径是不是指向你的android sdk的路径(我已经安装好Android Studio)，上面是写错了Documents，要改为Library
2.检查PATH=/Users/yingyou/Documents/flutter/bin:$PATH是否指向你解压flutter sdk的路径
3.再次执行 sourece ~/.basehrc 然后 flutter !
4.苹果应用商店安装xcode
5.在Anroid Studio 安装插件
Flutter、Dart（打开插件首选项 Preferences>Plugins )
6.安装brew及CocoaPods
安装brew: /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
安装CocoaPods: sudo gem install cocoapods
7.其他问题
flutter docto 提示以下信息：
Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel dev, v0.8.6, on Mac OS X 10.13.6 17G65, locale zh-Hans-CN)
[✗] Android toolchain - develop for Android devices
✗ ANDROID_HOME = /Users/yingyou/Documents/android/sdk
but Android SDK not found at this location.
[✗] iOS toolchain - develop for iOS devices
✗ Xcode installation is incomplete; a full installation is necessary for iOS development.
Download at: https://developer.apple.com/xcode/download/
Or install Xcode via the App Store.
Once installed, run:
sudo xcode-select --switch /Applications/Xcode.app/Contents/Developer
✗ Brew not installed; use this to install tools for iOS device development.
Download brew at https://brew.sh/.
[✓] Android Studio (version 3.1)
✗ Flutter plugin not installed; this adds Flutter specific functionality.
✗ Dart plugin not installed; this adds Dart specific functionality.
[!] Connected devices
! No devices available再终端一个个执行下面（执行后，flutter doctor还会提示，重启一下电脑即可）：
brew install --HEAD libimobiledevice
brew install ideviceinstaller
brew install ios-deploy
brew install cocoapods
pod setup
完毕！