使用pigeon开发Flutter插件

说明

使用pigeon，从0开发一个Flutter插件，支持Android、iOS平台，插件提供2个功能：

获取系统版本号。
在原生层，弹出一个Dialog。

新建项目

创建插件项目

通过flutter create命令，创建一个插件项目：

flutter create --template plugin --platforms android,ios --project-name cute --org com.yuluyao cute-plugin

项目结构：

hello_plugin/
├── android/
│   └── src/
│       └── main/
│           └── kotlin/com/yuluyao/cute/
│           │   └── CutePlugin.kt
│           └── AndroidManifest.xml
├── example/
├── ios/
│   └── Classes/
│       └── CutePlugin.swift
├── lib/
│   │── cute_method_channel.dart
│   │── cute_platform_interface.dart
│   └── cute.dart
├── pubspec.yaml

添加pigeon

添加pigeon依赖：

flutter pub add dev:pigeon

添加以后，pubspec.yaml中会多出1行：

pubspec.yaml

yaml

dev_dependencies:
  pigeon: ^22.5.0

使用pigeon

定义插件API

在项目根目录中，新建pigeon_host_api.dart文件，在其中定义2个API：

getSystemVersionInfo
popDialog

代码如下：

pigeon_host_api.dart

dart

import 'package:pigeon/pigeon.dart';

class SystemVersionInfo {
  SystemVersionInfo({required this.platform, required this.version});
  final String platform;
  final String version;
}

@ConfigurePigeon(
  PigeonOptions(
    // API
    dartOut: 'lib/pigeon/cute_api.g.dart',
    dartOptions: DartOptions(),
    dartPackageName: 'cute',

    // Android
    kotlinOut: 'android/src/main/kotlin/com/yuluyao/cute/Cute.g.kt',
    kotlinOptions: KotlinOptions(
      package: "com.yuluyao.cute",
    ),

    // iOS or macOS
    swiftOut: 'ios/Classes/Cute.g.swift',
    swiftOptions: SwiftOptions(),
  ),
)
@HostApi()
abstract class CuteHostApi {
  SystemVersionInfo getSystemVersionInfo();

  @async
  @SwiftFunction('popDialog(_:_:)')
  bool popDialog(String title, String message);
}

生成代码

命令：

dart run pigeon --input pigeon_host_api.dart

会生成3端的代码：

hello_plugin/
├── android/
│   └── src/
│       └── main/
│           └── kotlin/com/yuluyao/cute/
│           │   ├── Cute.g.kt
│           │   └── CutePlugin.kt
│           └── AndroidManifest.xml
├── example/
├── ios/
│   └── Classes/
│       ├── Cute.g.swift
│       └── CutePlugin.swift
├── lib/
│   ├── pigeon/
│   │   └── cute_api.g.dart
│   │── cute_method_channel.dart
│   │── cute_platform_interface.dart
│   └── cute.dart
├── pubspec.yaml

编译example项目

编辑原生项目代码之前，要先编译一次Flutter，确保Android Studio或XCode正确打开项目。

进入example目录：

编译Android编译iOS

flutter build apk --config-only

flutter build ios --no-codesign --config-only

Flutter端

生成的cute_api.g.dart文件中，有一个CuteHostApi，它已经处理了通过Method Channel调用原生的逻辑。

CuteHostApi即是本插件提供的API，可以供其它项目调用。

在example项目中调用：

dart

final api = CuteHostApi();
final info = await api.getSystemVersionInfo();
final ok = api.popDialog("title", "message");

所以，新建项目时，生成的Dart代码就不需要了，可以删除：

├── lib/
│   ├── pigeon/
│   │   └── cute_api.g.dart
│   │── cute_method_channel.dart
│   │── cute_platform_interface.dart
│   └── cute.dart

Android端

打开Android项目

用Android Studio打开example/android/build.gradle，打开以后要进行Gradle Sync。

INFO

Gradle Sync可能很慢，或连接失败，可以给Android Studio设置代理。

Sync完了以后，还要经过Build，也很慢。😅😅

项目结构与普通Android项目有点不一样：

（注意：这里是Android视图，不是Project视图！）

项目结构-Android视图

Android/
├── app/
│   │── manifests/
│   │── kotlin/
│   │   └── com.yuluyao.cute_example/
│   │       └── MainActivity.kt // 此文件没什么用
│   │── kotlin+java/
│   └── res/
├── cute/
│   │── manifests/
│   └── kotlin+java/
│       └── com.yuluyao.cute/
│           │── Cute.g.kt
│           └── CutePlugin.kt
├── integration_test/
├── gradle/

疑问：

既然上面的MainActivity没什么用，为什么还要用Android视图打开它呢？为什么不仅仅打开项目的android/build.gradle呢？毕竟CutePlugin.kt就在这个目录中。

答案是：

仅打开android/build.gradle，会到处报红色错误，无法正常编辑Kotlin代码。

代码分析

先看一下代码：

CutePlugin.ktCute.g.kt

kotlin

package com.yuluyao.cute

import androidx.annotation.NonNull

import io.flutter.embedding.engine.plugins.FlutterPlugin
import io.flutter.plugin.common.MethodCall
import io.flutter.plugin.common.MethodChannel
import io.flutter.plugin.common.MethodChannel.MethodCallHandler
import io.flutter.plugin.common.MethodChannel.Result

/** CutePlugin */
class CutePlugin: FlutterPlugin, MethodCallHandler {
  /// The MethodChannel that will the communication between Flutter and native Android
  ///
  /// This local reference serves to register the plugin with the Flutter Engine and unregister it
  /// when the Flutter Engine is detached from the Activity
  private lateinit var channel : MethodChannel

  override fun onAttachedToEngine(flutterPluginBinding: FlutterPlugin.FlutterPluginBinding) {
    channel = MethodChannel(flutterPluginBinding.binaryMessenger, "cute")
    channel.setMethodCallHandler(this)
  }

  override fun onMethodCall(call: MethodCall, result: Result) {
    if (call.method == "getPlatformVersion") {
      result.success("Android ${android.os.Build.VERSION.RELEASE}")
    } else {
      result.notImplemented()
    }
  }

  override fun onDetachedFromEngine(binding: FlutterPlugin.FlutterPluginBinding) {
    channel.setMethodCallHandler(null)
  }
}

kotlin

// Autogenerated from Pigeon (v22.5.0), do not edit directly.
// See also: https://pub.dev/packages/pigeon
@file:Suppress("UNCHECKED_CAST", "ArrayInDataClass")

package com.yuluyao.cute

import android.util.Log
import io.flutter.plugin.common.BasicMessageChannel
import io.flutter.plugin.common.BinaryMessenger
import io.flutter.plugin.common.MessageCodec
import io.flutter.plugin.common.StandardMessageCodec
import java.io.ByteArrayOutputStream
import java.nio.ByteBuffer

private fun wrapResult(result: Any?): List<Any?> {
  return listOf(result)
}

private fun wrapError(exception: Throwable): List<Any?> {
  return if (exception is FlutterError) {
    listOf(
      exception.code,
      exception.message,
      exception.details
    )
  } else {
    listOf(
      exception.javaClass.simpleName,
      exception.toString(),
      "Cause: " + exception.cause + ", Stacktrace: " + Log.getStackTraceString(exception)
    )
  }
}

/**
 * Error class for passing custom error details to Flutter via a thrown PlatformException.
 * @property code The error code.
 * @property message The error message.
 * @property details The error details. Must be a datatype supported by the api codec.
 */
class FlutterError (
  val code: String,
  override val message: String? = null,
  val details: Any? = null
) : Throwable()

/** Generated class from Pigeon that represents data sent in messages. */
data class SystemVersionInfo (
  val platform: String,
  val version: String
)
 {
  companion object {
    fun fromList(pigeonVar_list: List<Any?>): SystemVersionInfo {
      val platform = pigeonVar_list[0] as String
      val version = pigeonVar_list[1] as String
      return SystemVersionInfo(platform, version)
    }
  }
  fun toList(): List<Any?> {
    return listOf(
      platform,
      version,
    )
  }
}
private open class CutePigeonCodec : StandardMessageCodec() {
  override fun readValueOfType(type: Byte, buffer: ByteBuffer): Any? {
    return when (type) {
      129.toByte() -> {
        return (readValue(buffer) as? List<Any?>)?.let {
          SystemVersionInfo.fromList(it)
        }
      }
      else -> super.readValueOfType(type, buffer)
    }
  }
  override fun writeValue(stream: ByteArrayOutputStream, value: Any?)   {
    when (value) {
      is SystemVersionInfo -> {
        stream.write(129)
        writeValue(stream, value.toList())
      }
      else -> super.writeValue(stream, value)
    }
  }
}


/** Generated interface from Pigeon that represents a handler of messages from Flutter. */
interface CuteHostApi {
  fun getSystemVersionInfo(): SystemVersionInfo
  fun popDialog(title: String, message: String, callback: (Result<Boolean>) -> Unit)

  companion object {
    /** The codec used by CuteHostApi. */
    val codec: MessageCodec<Any?> by lazy {
      CutePigeonCodec()
    }
    /** Sets up an instance of `CuteHostApi` to handle messages through the `binaryMessenger`. */
    @JvmOverloads
    fun setUp(binaryMessenger: BinaryMessenger, api: CuteHostApi?, messageChannelSuffix: String = "") {
      val separatedMessageChannelSuffix = if (messageChannelSuffix.isNotEmpty()) ".$messageChannelSuffix" else ""
      run {
        val channel = BasicMessageChannel<Any?>(binaryMessenger, "dev.flutter.pigeon.cute.CuteHostApi.getSystemVersionInfo$separatedMessageChannelSuffix", codec)
        if (api != null) {
          channel.setMessageHandler { _, reply ->
            val wrapped: List<Any?> = try {
              listOf(api.getSystemVersionInfo())
            } catch (exception: Throwable) {
              wrapError(exception)
            }
            reply.reply(wrapped)
          }
        } else {
          channel.setMessageHandler(null)
        }
      }
      run {
        val channel = BasicMessageChannel<Any?>(binaryMessenger, "dev.flutter.pigeon.cute.CuteHostApi.popDialog$separatedMessageChannelSuffix", codec)
        if (api != null) {
          channel.setMessageHandler { message, reply ->
            val args = message as List<Any?>
            val titleArg = args[0] as String
            val messageArg = args[1] as String
            api.popDialog(titleArg, messageArg) { result: Result<Boolean> ->
              val error = result.exceptionOrNull()
              if (error != null) {
                reply.reply(wrapError(error))
              } else {
                val data = result.getOrNull()
                reply.reply(wrapResult(data))
              }
            }
          }
        } else {
          channel.setMessageHandler(null)
        }
      }
    }
  }
}

CutePlugin.kt：它是与Flutter端通信的入口，我们要实现Cute.g.kt中的CuteHostApi接口，并在CutePlugin.kt中调用它，以连接Android端与Flutter端。
Cute.g.kt：此文件由pigeon生成，不必修改，它帮我们处理了Method Channel通信、消息编解码、错误处理。

去掉默认代码

由于我们通过pigeon处理Method Channel通信，这里先去掉CutePlugin.kt中的Method Channel相关代码：

CutePlugin.kt（原代码）CutePlugin.kt（去掉后）

kotlin

package com.yuluyao.cute

import androidx.annotation.NonNull

import io.flutter.embedding.engine.plugins.FlutterPlugin
import io.flutter.plugin.common.MethodCall
import io.flutter.plugin.common.MethodChannel
import io.flutter.plugin.common.MethodChannel.MethodCallHandler
import io.flutter.plugin.common.MethodChannel.Result

/** CutePlugin */
class CutePlugin: FlutterPlugin, MethodCallHandler {
  /// The MethodChannel that will the communication between Flutter and native Android
  ///
  /// This local reference serves to register the plugin with the Flutter Engine and unregister it
  /// when the Flutter Engine is detached from the Activity
  private lateinit var channel : MethodChannel

  override fun onAttachedToEngine(flutterPluginBinding: FlutterPlugin.FlutterPluginBinding) {
    channel = MethodChannel(flutterPluginBinding.binaryMessenger, "cute")
    channel.setMethodCallHandler(this)
  }

  override fun onMethodCall(call: MethodCall, result: Result) {
    if (call.method == "getPlatformVersion") {
      result.success("Android ${android.os.Build.VERSION.RELEASE}")
    } else {
      result.notImplemented()
    }
  }

  override fun onDetachedFromEngine(binding: FlutterPlugin.FlutterPluginBinding) {
    channel.setMethodCallHandler(null)
  }
}

kotlin

package com.yuluyao.cute

import io.flutter.embedding.engine.plugins.FlutterPlugin

/** CutePlugin */
class CutePlugin: FlutterPlugin {

  override fun onAttachedToEngine(flutterPluginBinding: FlutterPlugin.FlutterPluginBinding) {
  }

  override fun onDetachedFromEngine(binding: FlutterPlugin.FlutterPluginBinding) {
  }
}

实现功能

代码：

kotlin

package com.yuluyao.cute

import android.app.Activity
import android.app.AlertDialog
import android.os.Build
import io.flutter.embedding.engine.plugins.FlutterPlugin
import io.flutter.embedding.engine.plugins.activity.ActivityAware
import io.flutter.embedding.engine.plugins.activity.ActivityPluginBinding

/** CutePlugin */
class CutePlugin : FlutterPlugin, ActivityAware {

  override fun onAttachedToEngine(flutterPluginBinding: FlutterPlugin.FlutterPluginBinding) {
    CuteHostApi.setUp(flutterPluginBinding.binaryMessenger, api)
  }

  override fun onDetachedFromEngine(binding: FlutterPlugin.FlutterPluginBinding) {
  }

  private val api = object : CuteHostApi {
    override fun getSystemVersionInfo(): SystemVersionInfo {
      return SystemVersionInfo(platform = "Android", version = Build.VERSION.SDK)
    }

    override fun popDialog(title: String, message: String, callback: (Result<Boolean>) -> Unit) {
      AlertDialog.Builder(activity)
        .setTitle(title)
        .setMessage(message)
        .setPositiveButton("ok") { dialog, which ->
          callback.invoke(Result.success(true))
        }
        .setNegativeButton("cancel") { dialog, which ->
          callback.invoke(Result.success(false))
        }
        .show()
    }
  }

  private var activity: Activity? = null
  override fun onAttachedToActivity(binding: ActivityPluginBinding) {
    activity = binding.activity
  }

  override fun onDetachedFromActivityForConfigChanges() {
    activity = null
  }

  override fun onReattachedToActivityForConfigChanges(binding: ActivityPluginBinding) {
    activity = binding.activity
  }

  override fun onDetachedFromActivity() {
    activity = null
  }
}

分析：

获取宿主Activity：

让CutePlugin实现ActivityAware接口，以获取当前的宿主Activity。

kotlin

class CutePlugin : FlutterPlugin, ActivityAware { 

  // ...

  private var activity: Activity? = null
  override fun onAttachedToActivity(binding: ActivityPluginBinding) {
    activity = binding.activity
  }

  override fun onDetachedFromActivityForConfigChanges() {
    activity = null
  }

  override fun onReattachedToActivityForConfigChanges(binding: ActivityPluginBinding) {
    activity = binding.activity
  }

  override fun onDetachedFromActivity() {
    activity = null
  }
}

实现CuteHostApi接口

kotlin

class CutePlugin : FlutterPlugin, ActivityAware {

  private val api = object : CuteHostApi { 
    override fun getSystemVersionInfo(): SystemVersionInfo {
      return SystemVersionInfo(platform = "Android", version = Build.VERSION.SDK)
    }

    override fun popDialog(title: String, message: String, callback: (Result<Boolean>) -> Unit) {
      AlertDialog.Builder(activity)
        .setTitle(title)
        .setMessage(message)
        .setPositiveButton("ok") { dialog, which ->
          callback.invoke(Result.success(true))
        }
        .setNegativeButton("cancel") { dialog, which ->
          callback.invoke(Result.success(false))
        }
        .show()
    }
  }

  // ...
}

连接Method Channel

kotlin

class CutePlugin : FlutterPlugin, ActivityAware {

  override fun onAttachedToEngine(flutterPluginBinding: FlutterPlugin.FlutterPluginBinding) {
    CuteHostApi.setUp(flutterPluginBinding.binaryMessenger, api) 
  }

  // ...

}

iOS端

打开iOS项目

用XCode打开example/ios/Runner.xcworkspace。

项目结构：

项目结构

Project navigator/
├── Runner/
│   │── Flutter/
│   │── Runner/
│   │── Products/
│   │── RunnerTests/
│   │── Pods/
│   └── Frameworks/
├── Pods/
│   │── Podfile
│   └── Development Pods/
│       └── cute/
│           └── ../
│               └── ../
│                   └── example/
│                       └── ios/
│                           └── symlinks/
│                               └── plugins/
│                                   └── cute/
│                                       └── ios/
│                                           └── Classes/
│                                               │── Cute.g.swift
│                                               └── CutePlugin.swift
├── Frameworks/
├── Products/
├── Targets Support Files/

代码分析

先看一下代码：

CutePlugin.swiftCute.g.swift

swift

import Flutter
import UIKit

public class CutePlugin: NSObject, FlutterPlugin {
  public static func register(with registrar: FlutterPluginRegistrar) {
    let channel = FlutterMethodChannel(name: "cute", binaryMessenger: registrar.messenger())
    let instance = CutePlugin()
    registrar.addMethodCallDelegate(instance, channel: channel)
  }

  public func handle(_ call: FlutterMethodCall, result: @escaping FlutterResult) {
    switch call.method {
    case "getPlatformVersion":
      result("iOS " + UIDevice.current.systemVersion)
    default:
      result(FlutterMethodNotImplemented)
    }
  }
}

swift

// Autogenerated from Pigeon (v22.5.0), do not edit directly.
// See also: https://pub.dev/packages/pigeon

import Foundation

#if os(iOS)
  import Flutter
#elseif os(macOS)
  import FlutterMacOS
#else
  #error("Unsupported platform.")
#endif

/// Error class for passing custom error details to Dart side.
final class PigeonError: Error {
  let code: String
  let message: String?
  let details: Any?

  init(code: String, message: String?, details: Any?) {
    self.code = code
    self.message = message
    self.details = details
  }

  var localizedDescription: String {
    return
      "PigeonError(code: \(code), message: \(message ?? "<nil>"), details: \(details ?? "<nil>")"
      }
}

private func wrapResult(_ result: Any?) -> [Any?] {
  return [result]
}

private func wrapError(_ error: Any) -> [Any?] {
  if let pigeonError = error as? PigeonError {
    return [
      pigeonError.code,
      pigeonError.message,
      pigeonError.details,
    ]
  }
  if let flutterError = error as? FlutterError {
    return [
      flutterError.code,
      flutterError.message,
      flutterError.details,
    ]
  }
  return [
    "\(error)",
    "\(type(of: error))",
    "Stacktrace: \(Thread.callStackSymbols)",
  ]
}

private func isNullish(_ value: Any?) -> Bool {
  return value is NSNull || value == nil
}

private func nilOrValue<T>(_ value: Any?) -> T? {
  if value is NSNull { return nil }
  return value as! T?
}

/// Generated class from Pigeon that represents data sent in messages.
struct SystemVersionInfo {
  var platform: String
  var version: String



  // swift-format-ignore: AlwaysUseLowerCamelCase
  static func fromList(_ pigeonVar_list: [Any?]) -> SystemVersionInfo? {
    let platform = pigeonVar_list[0] as! String
    let version = pigeonVar_list[1] as! String

    return SystemVersionInfo(
      platform: platform,
      version: version
    )
  }
  func toList() -> [Any?] {
    return [
      platform,
      version,
    ]
  }
}

private class CutePigeonCodecReader: FlutterStandardReader {
  override func readValue(ofType type: UInt8) -> Any? {
    switch type {
    case 129:
      return SystemVersionInfo.fromList(self.readValue() as! [Any?])
    default:
      return super.readValue(ofType: type)
    }
  }
}

private class CutePigeonCodecWriter: FlutterStandardWriter {
  override func writeValue(_ value: Any) {
    if let value = value as? SystemVersionInfo {
      super.writeByte(129)
      super.writeValue(value.toList())
    } else {
      super.writeValue(value)
    }
  }
}

private class CutePigeonCodecReaderWriter: FlutterStandardReaderWriter {
  override func reader(with data: Data) -> FlutterStandardReader {
    return CutePigeonCodecReader(data: data)
  }

  override func writer(with data: NSMutableData) -> FlutterStandardWriter {
    return CutePigeonCodecWriter(data: data)
  }
}

class CutePigeonCodec: FlutterStandardMessageCodec, @unchecked Sendable {
  static let shared = CutePigeonCodec(readerWriter: CutePigeonCodecReaderWriter())
}


/// Generated protocol from Pigeon that represents a handler of messages from Flutter.
protocol CuteHostApi {
  func getSystemVersionInfo() throws -> SystemVersionInfo
  func popDialog(_ title: String, _ message: String, completion: @escaping (Result<Bool, Error>) -> Void)
}

/// Generated setup class from Pigeon to handle messages through the `binaryMessenger`.
class CuteHostApiSetup {
  static var codec: FlutterStandardMessageCodec { CutePigeonCodec.shared }
  /// Sets up an instance of `CuteHostApi` to handle messages through the `binaryMessenger`.
  static func setUp(binaryMessenger: FlutterBinaryMessenger, api: CuteHostApi?, messageChannelSuffix: String = "") {
    let channelSuffix = messageChannelSuffix.count > 0 ? ".\(messageChannelSuffix)" : ""
    let getSystemVersionInfoChannel = FlutterBasicMessageChannel(name: "dev.flutter.pigeon.cute.CuteHostApi.getSystemVersionInfo\(channelSuffix)", binaryMessenger: binaryMessenger, codec: codec)
    if let api = api {
      getSystemVersionInfoChannel.setMessageHandler { _, reply in
        do {
          let result = try api.getSystemVersionInfo()
          reply(wrapResult(result))
        } catch {
          reply(wrapError(error))
        }
      }
    } else {
      getSystemVersionInfoChannel.setMessageHandler(nil)
    }
    let popDialogChannel = FlutterBasicMessageChannel(name: "dev.flutter.pigeon.cute.CuteHostApi.popDialog\(channelSuffix)", binaryMessenger: binaryMessenger, codec: codec)
    if let api = api {
      popDialogChannel.setMessageHandler { message, reply in
        let args = message as! [Any?]
        let titleArg = args[0] as! String
        let messageArg = args[1] as! String
        api.popDialog(titleArg, messageArg) { result in
          switch result {
          case .success(let res):
            reply(wrapResult(res))
          case .failure(let error):
            reply(wrapError(error))
          }
        }
      }
    } else {
      popDialogChannel.setMessageHandler(nil)
    }
  }
}

CutePlugin.swift：它是与Flutter端通信的入口，我们要实现Cute.g.swift中的CuteHostApi接口，并在CutePlugin.swift中调用它，以连接iOS端与Flutter端。
Cute.g.swift：此文件由pigeon生成，不必修改，它帮我们处理了Method Channel通信、消息编解码、错误处理。

去掉默认代码

由于我们通过pigeon处理Method Channel通信，这里先去掉CutePlugin.swift中的Method Channel相关代码：

CutePlugin.kt（原代码）CutePlugin.swift（去掉后）

kotlin

import Flutter
import UIKit

public class CutePlugin: NSObject, FlutterPlugin {
  public static func register(with registrar: FlutterPluginRegistrar) {
    let channel = FlutterMethodChannel(name: "cute", binaryMessenger: registrar.messenger())
    let instance = CutePlugin()
    registrar.addMethodCallDelegate(instance, channel: channel)
  }

  public func handle(_ call: FlutterMethodCall, result: @escaping FlutterResult) {
    switch call.method {
    case "getPlatformVersion":
      result("iOS " + UIDevice.current.systemVersion)
    default:
      result(FlutterMethodNotImplemented)
    }
  }
}

kotlin

import Flutter
import UIKit

public class CutePlugin: NSObject, FlutterPlugin {
  public static func register(with registrar: FlutterPluginRegistrar) {
  }

}

实现功能

代码：

swift

import Flutter
import UIKit

public class CutePlugin: NSObject, FlutterPlugin {
    
  public static func register(with registrar: FlutterPluginRegistrar) {
      let api = CuteHostApiImpl()
      CuteHostApiSetup.setUp(binaryMessenger: registrar.messenger(), api: api)
  }

    private class CuteHostApiImpl : CuteHostApi {
        func getSystemVersionInfo() throws -> SystemVersionInfo {
            return SystemVersionInfo(platform: "iOS", version: UIDevice.current.systemVersion)
        }

        func popDialog(_ title: String, _ message: String, completion: @escaping (Result<Bool, Error>) -> Void) {
            if let viewController = UIApplication.shared.keyWindow?.rootViewController {
                let alertController = UIAlertController(title: title, message: message, preferredStyle: .alert)
                let okAction = UIAlertAction(title: "OK", style: .default) { (action) in
                    completion(.success(true))
                }
                let cancelAction = UIAlertAction(title: "Cancel", style: .cancel) { (action) in
                    completion(.success(false))
                }
                alertController.addAction(okAction)
                alertController.addAction(cancelAction)
                viewController.present(alertController, animated: true, completion: nil)
            }
          
        }
    }
}

分析：

获取UIViewController

swift

if let viewController = UIApplication.shared.keyWindow?.rootViewController {
  // ...
}

实现CuteHostApi接口

swift

public class CutePlugin: NSObject, FlutterPlugin {

  private class CuteHostApiImpl : CuteHostApi { 
      func getSystemVersionInfo() throws -> SystemVersionInfo {
          return SystemVersionInfo(platform: "iOS", version: UIDevice.current.systemVersion)
      }

      func popDialog(_ title: String, _ message: String, completion: @escaping (Result<Bool, Error>) -> Void) {
          if let viewController = UIApplication.shared.keyWindow?.rootViewController {
              let alertController = UIAlertController(title: title, message: message, preferredStyle: .alert)
              let okAction = UIAlertAction(title: "OK", style: .default) { (action) in
                  completion(.success(true))
              }
              let cancelAction = UIAlertAction(title: "Cancel", style: .cancel) { (action) in
                  completion(.success(false))
              }
              alertController.addAction(okAction)
              alertController.addAction(cancelAction)
              viewController.present(alertController, animated: true, completion: nil)
          }
        
      }
  }
}

连接Method Channel

swift

public static func register(with registrar: FlutterPluginRegistrar) {
    let api = CuteHostApiImpl()
    CuteHostApiSetup.setUp(binaryMessenger: registrar.messenger(), api: api) 
}

使用此插件

可以在example/中使用此插件的API。

example/lib/main.dart：

dart

import 'package:cute/pigeon/cute_api.g.dart';
import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatefulWidget {
  const MyApp({super.key});

  @override
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  late final CuteHostApi hostApi;
  SystemVersionInfo? _systemVersionInfo;
  bool clickOK = false;

  @override
  void initState() {
    super.initState();
    hostApi = CuteHostApi();
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Cute plugin example app'),
        ),
        body: Center(
          child: Column(
            children: [
              const SizedBox(height: 40),
              Text("系统版本号：${_systemVersionInfo?.platform}, ${_systemVersionInfo?.version}"),
              OutlinedButton(
                onPressed: () async {
                  final s = await hostApi.getSystemVersionInfo();
                  setState(() {
                    _systemVersionInfo = s;
                  });
                },
                child: const Text('获取系统版本号'),
              ),
              const SizedBox(height: 40),
              Text("用户已选OK？ $clickOK"),
              OutlinedButton(
                onPressed: () async {
                  final ok = await hostApi.popDialog("title", "来自Flutter的message");
                  setState(() {
                    clickOK = ok;
                  });
                },
                child: const Text('弹出原生Dialog'),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

使用pigeon开发Flutter插件 ​

说明 ​

新建项目 ​

创建插件项目 ​

添加pigeon ​

使用pigeon ​

定义插件API ​

生成代码 ​

编译example项目 ​

Flutter端 ​

Android端 ​

打开Android项目 ​

代码分析 ​

去掉默认代码 ​

实现功能 ​

iOS端 ​

打开iOS项目 ​

代码分析 ​

去掉默认代码 ​

实现功能 ​

使用此插件 ​

使用pigeon开发Flutter插件

说明

新建项目

创建插件项目

添加pigeon

使用pigeon

定义插件API

生成代码

编译example项目

Flutter端

Android端

打开Android项目

代码分析

去掉默认代码

实现功能

iOS端

打开iOS项目

代码分析

去掉默认代码

实现功能

使用此插件