3. flutter初體驗

安裝Dart及Flutter

安裝Chocolatey：https://chocolatey.org/ （管理員身份+power shell）

Set-ExecutionPolicy Bypass -Scope Process -Force; iex ((New-Object System.Net.WebClient).DownloadString('https://chocolatey.org/install.ps1'))

安裝Dart SDK（管理員身份+power shell）
```
choco install dart-sdk
```
看起來像這樣：
接著請於 VS Code 編輯器安裝各種關於Dart以及flutter的外掛。
https://flutter.io/setup-windows/ 下載 flutter_windows_xxx.zip，並解壓縮到 C:\tools 底下即可
編輯環境變數，加入 C:\tools\flutter\bin 即可
執行C:\tools\flutter\flutter_console.bat即可在flutter命令列運行flutter命令
日後要更新flutter只要在終端機輸入以下指令即可：
```
flutter upgrade
```
要驗證設定只要在終端機輸入（在VSCode中按Ctrl+`即可）以下指令即可：
```
flutter doctor
```
安裝 Android Studio, 3.0或更高版本
點擊 Configation→plugin→Browse repositories…，安裝和flutter相關的外掛
建立新的flutter專案，然後從 Tools→AVD Manager 去新增模擬器

如果執行F5跑模擬器時，遇到以下問題

Launching lib\main.dart on Android SDK built for x86 in debug mode...
Initializing gradle...
Resolving dependencies...
Finished with error: Please review your Gradle project setup in the android/ folder.
* Error running Gradle:
Exit code 1 from: D:\tad\app1\android\gradlew.bat app:properties:
Project evaluation failed including an error in afterEvaluate {}. Run with --stacktrace for details of the afterEvaluate {} error.

FAILURE: Build failed with an exception.

* Where:
Build file 'D:\tad\app1\android\app\build.gradle' line: 25

* What went wrong:
A problem occurred evaluating project ':app'.
> Could not resolve all files for configuration 'classpath'.
   > Could not find lint-gradle-api.jar (com.android.tools.lint:lint-gradle-api:26.1.2).
     Searched in the following locations:
         https://jcenter.bintray.com/com/android/tools/lint/lint-gradle-api/26.1.2/lint-gradle-api-26.1.2.jar

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 2s

請修改C:\tools\flutter\packages\flutter_tools\gradle\flutter.gradle，把jcenter()位置調整一下及即可：

buildscript {
    repositories {

        jcenter()
        maven {
            url 'https://dl.google.com/dl/android/maven2'
        }

    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.1.2'
    }
}

改為

buildscript {
    repositories {
        maven {
            url 'https://dl.google.com/dl/android/maven2'
        }
        jcenter()

    }
    dependencies {`enter code here`
        classpath 'com.android.tools.build:gradle:3.1.2'
    }
}

IOS安裝

https://astr0baby.wordpress.com/2018/04/22/installing-high-sierra-10-13-4-in-virtualbox-5-x/?fbclid=IwAR2z8Ks4VFS-IdufpuoVtjgM2hVzYUGqofpmzJjlNKKHcQJp2t1SEoPCjlM
下載 VirtualBox 並安裝
下載 MacOS 10.13.4 iso 並解壓縮
啟動VirtualBox，並建立新電腦
- 名稱: High Sierra
- 類型: Mac OS X
- 版本: macOS High Sierra (64-bit)
2個CPU
記憶體至少 4 GB ( 或 70% 記憶體 )
顯示記憶體 128MB
在光碟掛載剛剛下載的MacOSHighSierra10.13.4.iso檔

到終端機輸入：

cd "C:\Program Files\Oracle\VirtualBox\"
VBoxManage modifyvm "High Sierra" --cpuidset 00000001 000106e5 00100800 0098e3fd bfebfbff
VBoxManage setextradata "High Sierra" "VBoxInternal/Devices/efi/0/Config/DmiSystemProduct" "iMac11,3"
VBoxManage setextradata "High Sierra" "VBoxInternal/Devices/efi/0/Config/DmiSystemVersion" "1.0"
VBoxManage setextradata "High Sierra" "VBoxInternal/Devices/efi/0/Config/DmiBoardProduct" "Iloveapple"
VBoxManage setextradata "High Sierra" "VBoxInternal/Devices/smc/0/Config/DeviceKey" "ourhardworkbythesewordsguardedpleasedontsteal(c)AppleComputerInc"
VBoxManage setextradata "High Sierra" "VBoxInternal/Devices/smc/0/Config/GetKeyFromRealSMC" 1