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Description:

nearby connections

nearby_connections #
An ANDROID flutter plugin for the Nearby Connections API
Currently supports Bytes and Files.
Transfer Data between multiple connected devices using fully offline peer to peer networking

Table of Content #

Setup
Work Flow

Advertise For connections
Discover Advertisers
Request Connection
Accept Connection

Sending Data

Sending Bytes Payload
Sending Files

Setup #
Note regarding Location(GPS) #
While using this,
Location/GPS service must be turned on or devices may disconnect
more often, some devices may disconnect immediately.
Set Permissions #
Add these to your project's android/src/main/AndroidManifest.xml

<uses-permission android:maxSdkVersion="31" android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:maxSdkVersion="31" android:name="android.permission.CHANGE_WIFI_STATE" />
<uses-permission android:maxSdkVersion="30" android:name="android.permission.BLUETOOTH" />
<uses-permission android:maxSdkVersion="30" android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:maxSdkVersion="28" android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:minSdkVersion="29" android:maxSdkVersion="31" android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:minSdkVersion="31" android:name="android.permission.BLUETOOTH_ADVERTISE" />
<uses-permission android:minSdkVersion="31" android:name="android.permission.BLUETOOTH_CONNECT" />
<uses-permission android:minSdkVersion="31" android:name="android.permission.BLUETOOTH_SCAN" />
<uses-permission android:minSdkVersion="32" android:name="android.permission.NEARBY_WIFI_DEVICES" />

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
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Note: Android 12+ has introduced some new bluetooth permissions - BLUETOOTH_ADVERTISE, BLUETOOTH_CONNECT, BLUETOOTH_SCAN, which need to be handled as well. You may also need to set compileSdkVersion 32 in your build.gradle file.

Request Permissions #
Since ACCESS_FINE_LOCATION, BLUETOOTH_ADVERTISE, BLUETOOTH_CONNECT, BLUETOOTH_SCAN and READ_EXTERNAL_STORAGE are considered to be dangerous system permissions, in addition to adding them to your manifest, you must request these permissions at runtime.

You can use:

permission_handler package to handle all these permissions
location package to request enabling location.
device_info_plus to check Android verison.

// location permission
await Permission.location.isGranted // Check Permission
await Permission.location.request() // Ask

// Check Location Status
await Permission.location.serviceStatus.isEnabled;

// location enable dialog
await Location.instance.requestService()

// external storage permission
await Permission.storage.isGranted // Check Permission
await Permission.storage.request() // Ask

// Bluetooth permissions
bool granted = !(await Future.wait([ // Check Permissions
Permission.bluetooth.isGranted,
Permission.bluetoothAdvertise.isGranted,
Permission.bluetoothConnect.isGranted,
Permission.bluetoothScan.isGranted,
])).any((element) => false);
[ // Ask Permissions
Permission.bluetooth,
Permission.bluetoothAdvertise,
Permission.bluetoothConnect,
Permission.bluetoothScan
].request();

// Check Bluetooth Status
await Permission.bluetooth.serviceStatus.isEnabled;

// Android 12+
await Permission.nearbyWifiDevices.request()
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Checkout the Example in Repository for more details.
NOTE #
Location/GPS service must be turned on or devices may disconnect
more often, some devices may disconnect immediately.
Work Flow #
The work flow is similar to the Android Nearby Connections library
Advertise for connection #
try {
bool a = await Nearby().startAdvertising(
userName,
strategy, // https://developers.google.com/nearby/connections/strategies
onConnectionInitiated: (String id,ConnectionInfo info) {
// Called whenever a discoverer requests connection
},
onConnectionResult: (String id,Status status) {
// Called when connection is accepted/rejected
},
onDisconnected: (String id) {
// Callled whenever a discoverer disconnects from advertiser
},
serviceId: "com.yourdomain.appname", // uniquely identifies your app
);
} catch (exception) {
// platform exceptions like unable to start bluetooth or insufficient permissions
}
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Discover Advertisers #
try {
bool a = await Nearby().startDiscovery(
userName,
strategy, // https://developers.google.com/nearby/connections/strategies
onEndpointFound: (String id,String userName, String serviceId) {
// called when an advertiser is found
},
onEndpointLost: (String id) {
//called when an advertiser is lost (only if we weren't connected to it )
},
serviceId: "com.yourdomain.appname", // uniquely identifies your app
);
} catch (e) {
// platform exceptions like unable to start bluetooth or insufficient permissions
}
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Stopping Advertising and Discovery #
Nearby().stopAdvertising();
Nearby().stopDiscovery();
// endpoints already discovered will still be available to connect
// even after stopping discovery
// You should stop discovery once you have found the intended advertiser
// this will reduce chances for disconnection
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Request Connection #
// to be called by discover whenever an endpoint is found
// callbacks are similar to those in startAdvertising method
try{
Nearby().requestConnection(
userName,
id,
onConnectionInitiated: (id, info) {
},
onConnectionResult: (id, status) {
},
onDisconnected: (id) {
},
);
}catch(exception){
// called if request was invalid
}
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Accept Connection #
Nearby().acceptConnection(
id,
onPayLoadRecieved: (endpointId, payload) {
// called whenever a payload is recieved.
},
onPayloadTransferUpdate: (endpointId, payloadTransferUpdate) {
// gives status of a payload
// e.g success/failure/in_progress
// bytes transferred and total bytes etc
}
);
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Sending Data #
Sending Bytes Payload #
Nearby().sendBytesPayload(endpointId, bytes_array);

// payloads are recieved by callback given to acceptConnection method.
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Sending File Payload #
You need to send the File Payload and File Name seperately.
File is stored in DOWNLOAD_DIRECTORY/.nearby/ and given a generic name.
You need to copy the file to another directory of your choice.
//creates file with generic name (without extension) in Downloads Directory
//its your responsibility to rename the file properly
Nearby().sendFilePayload(endpointId, filePath);

//Send filename as well so that receiver can move and rename the file
Nearby().sendBytesPayload(endpointId,fileNameEncodedWithPayloadId);
//e.g send a string like "payloadId:FileExtensionOrFullName" as bytes

//payloads are recieved by callback given to acceptConnection method.
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Every payload has an ID which is same for sender and receiver.
You can get the uri of the file from Payload in onPayloadReceived function.
We have a convenience method to copy the file to a location you want-
// Convenience method to copy file using it's `uri`.
final newPath = '${await getExternalStorageDirectory}/$fileName';
await Nearby().copyFileAndDeleteOriginal(uri, newPath);
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Checkout the Example in Repository for more details.