plugin_scaffold 1.0.0

A new flutter plugin project.

Flutter Plugin Scaffold

Tired of endless switch-cases in your Flutter plugin code? This module is for you!

TLDR

It lets you turn this:-

channel.setMethodCallHandler { call, result ->
  when (call.method) {
    "orange" -> ...
    "banana" -> ...
    "mango" -> ...
    "apple" -> ...
    .
    .
    .
  }
}

Into this beauty:-

import com.pycampers.plugin_scaffold.createPluginScaffold


class MyPlugin {
    fun orange(call: MethodCall, result: Result) {
        ...
    }

    fun banana(call: MethodCall, result: Result) {
        ...
    }

    fun mango(call: MethodCall, result: Result) {
        ...
    }

    fun apple(call: MethodCall, result: Result) {
        ...
    }

    .
    .
    .
}

createPluginScaffold("myFancyChannel", registrar.messenger(), MyPlugin())

Install

Add this line to ios/<plugin-name>.podspec

s.dependency 'plugin_scaffold'

Add this line to android/build.gradle

dependencies {
    implementation project(path: ':plugin_scaffold')
    ...
}

Errors

Any errors that occur in native code tend to instantly crash the app. Sending them back to flutter can be a real PITA.

This module does everything in its power to prevent such mishaps.

import com.pycampers.method_call_dispatcher.MethodCallDispatcher
import com.pycampers.method_call_dispatcher.trySend


class MyPlugin {
    fun myBrokenMethod(call: MethodCall, result: MethodChannel.Result) {
        // This won't crash the app!
        // The exception will be serialized to flutter, and is catch-able in flutter.
        throw IllegalArgumentException("Hello from Kotlin!")
    }

    fun myBrokenCallbackMethod(call: MethodCall, result: MethodChannel.Result) {
        // Automatic exception handling can only work in non-callback, synchronous contexts.
        //
        // So, trySend guarantees that app won't crash,
        // and errors will be serialized to flutter,
        // even in a callback context.
        java.util.Timer().schedule(
            object : java.util.TimerTask() {
                override fun run() {
                    trySend(result) {
                        throw IllegalArgumentException("Hello from Kotlin!")
                    }
                }
            },
            1000
        )
    }
}

And yes, You get 100% dart catch-able PlatformExceptions with stacktraces of native code!

D/MethodCallDispatcher( 3572): piping exception to flutter: java.lang.IllegalArgumentException: Hello from Kotlin!
E/flutter ( 3572): [ERROR:flutter/lib/ui/ui_dart_state.cc(148)] Unhandled Exception: PlatformException(java.lang.IllegalArgumentException, Hello from Kotlin!, java.lang.IllegalArgumentException: Hello from Kotlin!
E/flutter ( 3572): 	at com.pycampers.method_call_dispatcher_example.MyPlugin$myBrokenCallbackMethod$1$run$1.invoke(MainActivity.kt:33)
E/flutter ( 3572): 	at com.pycampers.method_call_dispatcher_example.MyPlugin$myBrokenCallbackMethod$1$run$1.invoke(MainActivity.kt:30)
E/flutter ( 3572): 	at com.pycampers.method_call_dispatcher.MethodCallDispatcherPluginKt.trySend(MethodCallDispatcherPlugin.kt:52)
E/flutter ( 3572): 	at com.pycampers.method_call_dispatcher_example.MyPlugin$myBrokenCallbackMethod$1.run(MainActivity.kt:32)
E/flutter ( 3572): 	at java.util.Timer$TimerImpl.run(Timer.java:284)
E/flutter ( 3572): )

Example app

See the example app available @ main.dart & MainActivity.kt

Installation is same as for any other flutter plugin, except that this one doesn't have any dart code :-)

The core plugin code can be found at MethodCallDispatcherPlugin.kt

iOS

import plugin_scaffold


enum MyError: Error {
    case fatalError
}

func myFancyMethod(call _: FlutterMethodCall, result: @escaping FlutterResult) {
    // trySend is not required, but serves as a precautionary measure against errors.
    // useful in callbacks
    trySend(result) {
        "Hello from Swift!"
    }
}

func myBrokenMethod(call _: FlutterMethodCall, result _: @escaping FlutterResult) throws {
    throw MyError.fatalError
}

func myBrokenCallbackMethod(call _: FlutterMethodCall, result _: @escaping FlutterResult) throws {
    throw NSError(domain: "hello", code: 123)
}

// unfortunately, swift just isn't dynamic enough to make full-scale dynamic dispatch possible :(
createPluginScaffold(
    messenger: messenger,
    channelName: "myFancyChannel",
    methodMap: [
        "myFancyMethod": myFancyMethod,
        "myBrokenMethod": myBrokenMethod,
        "myBrokenCallbackMethod": myBrokenCallbackMethod,
    ]
)

Errors are piped as well:

[VERBOSE-2:ui_dart_state.cc(148)] Unhandled Exception: PlatformException(Runner.MyError.fatalError, The operation couldn’t be completed. (Runner.MyError error 0.), 0   plugin_scaffold                     0x0000000106131435 $s15plugin_scaffold14serializeErrorySo07FlutterD0CypF + 309
1   plugin_scaffold                     0x0000000106135a39 $s15plugin_scaffold20createPluginScaffold9messenger11channelName9methodMap05eventJ0So20FlutterMethodChannelC_SDySSSo0l5EventN0CGtSo0L15BinaryMessenger_p_SSSDySSypGSDySSSo0L13StreamHandler_So8NSObjectpGtFySo0lM4CallC_yypSgctcfU_yycfU_ASycfU_ + 121
2   plugin_scaffold                     0x000000010613654d $s15plugin_scaffold20createPluginScaffold9messenger11channelName9methodMap05eventJ0So20FlutterMethodChannelC_SDySSSo0l5EventN0CGtSo0L15BinaryMessenger_p_SSSDySSypGSDySSSo0L13StreamHandler_So8NSObjectpGtFySo0lM4CallC_yypSgctcfU_yycfU_ASycfU_TA + 13
3   plugin_scaffold                     0x0000000106133099 $s15plugin_scaffold7trySendyyyypSgc_ACyKcSgtFyycfU_ + 297
<…>
[VERBOSE-2:ui_dart_state.cc(148)] Unhandled Exception: PlatformException(Error Domain=hello Code=123 "(null)", The operation couldn’t be completed. (hello error 123.), 0   plugin_scaffold                     0x0000000106131435 $s15plugin_scaffold14serializeErrorySo07FlutterD0CypF + 309
1   plugin_scaffold                     0x0000000106135a39 $s15plugin_scaffold20createPluginScaffold9messenger11channelName9methodMap05eventJ0So20FlutterMethodChannelC_SDySSSo0l5EventN0CGtSo0L15BinaryMessenger_p_SSSDySSypGSDySSSo0L13StreamHandler_So8NSObjectpGtFySo0lM4CallC_yypSgctcfU_yycfU_ASycfU_ + 121
2   plugin_scaffold                     0x000000010613654d $s15plugin_scaffold20createPluginScaffold9messenger11channelName9methodMap05eventJ0So20FlutterMethodChannelC_SDySSSo0l5EventN0CGtSo0L15BinaryMessenger_p_SSSDySSypGSDySSSo0L13StreamHandler_So8NSObjectpGtFySo0lM4CallC_yypSgctcfU_yycfU_ASycfU_TA + 13
3   plugin_scaffold                     0x0000000106133099 $s15plugin_scaffold7trySendyyyypSgc_ACyKcSgtFyycfU_ + <…>