How to pass a message from Flutter to Native?

How would you pass info from Flutter back to Android/Native code if needed to interact with a specific API / hardware component?

Are there any Event Channels that can send info the other way or something similar to a callback?

1. The [platform_channel][1] documentation points out "method calls can also be sent in the reverse direction, with the platform acting as client to methods implemented in Dart. A concrete example of this is the [quick_actions plugin][2]." I don't see how the native side is receiving a message from Flutter in this instance.
2. It looks like a [BasicMessageChannel][3]’s send() method can be used to send "the specified message to the platform plugins on this channel". Can anyone provide a simple implementation example of this?


[1]:

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[2]:

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[3]:

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Yes, flutter does has an [`EventChannel`](

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) class which is what you are looking for exactly.

[Here](

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) is an example of that demonstrates how `MethodChannel` and `EventChannel` can be implemented. And
[this](

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) medium article shows how an `EventChannel` can be implemented in flutter.

Hope that helped!

**Objective C**

```
call.arguments[@"parameter"]
```

**Android**

```
call.argument("parameter");
```

for swift

guard let args = call.arguments as? [String : Any] else {return}
let phoneNumber = args["contactNumber"] as! String
let originalMessage = args["message"] as! String

If anyone wants to share the data from native to flutter with invoke method
follow this:

main.dart

Future<dynamic> handlePlatformChannelMethods() async {
platform.setMethodCallHandler((methodCall) async {
if (methodCall.method == "nativeToFlutter") {
String text = methodCall.arguments;
List<String> result = text.split(' ');
String user = result[0];
String message = result[1];
}
}
}

MainActivity.java

nativeToFlutter(text1:String?,text2:String?){
MethodChannel(flutterEngine!!.dartExecutor.binaryMessenger,
CHANNEL.invokeMethod("nativeToFlutter",text1+" "+text2);
}

This is a simple implementation showcasing:

1. Passing a string Value from flutter to Android code
2. Getting back response from Android code to flutter

Code is based on example from:

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1. Passing string value "text":

```dart
String text = "whatever";

Future<Null> _getBatteryLevel(text) async {
String batteryLevel;
try {
final String result = await platform.invokeMethod('getBatteryLevel',{"text":text});
batteryLevel = 'Battery level at $result % .';
} on PlatformException catch (e) {
batteryLevel = "Failed to get battery level: '${e.message}'.";
}

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

2. Getting back response "batterylevel" after RandomFunction();

```dart
public void onMethodCall(MethodCall call, MethodChannel.Result result) {
if (call.method.equals("getBatteryLevel")) {

text = call.argument("text");
String batteryLevel = RandomFunction(text);

if (batteryLevel != null) {
result.success(batteryLevel);
} else {
result.error("UNAVAILABLE", "Battery level not available.", null);
}
} else {
result.notImplemented();
}
}
```

Passing from Flutter to native:

await platform.invokeMethod('runModel',
{'path': imagePath!.path} // 'path' is the key here to be passed to Native side
);

For Android (Kotlin):

val hashMap = call.arguments as HashMap<*,*> //Get the arguments as a HashMap

val path = hashMap["path"] //Get the argument based on the key passed from Flutter

For iOS (Swift):

guard let args = call.arguments as? [String : Any] else {return}
let text = args["path"] as! String