Why platform channels bridge native code in Flutter - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to send a message from Flutter to native code using platform channels.

Flutter

static const platform = MethodChannel('[1]');

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Acom.example.app/channel

Bflutter/native

Capp/platform

Dnative/bridge

Attempts:

3 left

💡 Hint

Common Mistakes

Using a channel name that does not match the native side.

Leaving the channel name empty or generic.

The channel name must match on both Flutter and native sides to communicate properly.

2fill in blank

medium

Complete the code to invoke a native method called 'getBatteryLevel' from Flutter.

Flutter

final int batteryLevel = await platform.invokeMethod('[1]');

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AreadBattery

BfetchBattery

CbatteryStatus

DgetBatteryLevel

Attempts:

3 left

💡 Hint

Common Mistakes

Using a method name that does not exist on the native side.

Misspelling the method name.

The method name must exactly match the native method name to call it correctly.

3fill in blank

hard

Fix the error in the native Android code to receive messages from Flutter on the platform channel.

Flutter

new MethodChannel(getFlutterEngine().getDartExecutor().getBinaryMessenger(), "[1]")
  .setMethodCallHandler((call, result) -> {
    if (call.method.equals("getBatteryLevel")) {
      int batteryLevel = getBatteryLevel();
      if (batteryLevel != -1) {
        result.success(batteryLevel);
      } else {
        result.error("UNAVAILABLE", "Battery level not available.", null);
      }
    } else {
      result.notImplemented();
    }
  });

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Acom.example.app/channel

Bflutter/native

Cnative/bridge

Dapp/platform

Attempts:

3 left

💡 Hint

Common Mistakes

Using different channel names on Flutter and native sides.

Typos in the channel name string.

The channel name must match the one used in Flutter to establish communication.

4fill in blank

hard

Fill both blanks to complete the Flutter code that listens for native method calls and responds.

Flutter

platform.setMethodCallHandler((call) async {
  if (call.method == '[1]') {
    final String response = await getNativeData();
    return [2].success(response);
  } else {
    return [2].notImplemented();
  }
});

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AfetchData

Bresult

Ccall

Dresponse

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong method names that don't match native calls.

Confusing the call object with the result object.

The method name must match the native call, and the result object is used to send responses back.

5fill in blank

hard

Fill all three blanks to create a platform channel in Flutter that sends a message and handles exceptions.

Flutter

try {
  final int result = await platform.invokeMethod('[1]');
  print('Result: ' + result.toString());
} on [2] catch (e) {
  print('Failed to get result: ' + e.[3]);
}

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AgetBatteryLevel

BPlatformException

Cmessage

DMissingPluginException

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong exception types.

Accessing wrong properties of the exception.

The method name is 'getBatteryLevel'. The exception type is PlatformException. The error message is accessed via the 'message' property.