feat: Add `getBatteryLevel()` for checking the current battery-level of the device (#359)

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ### next
 
+* Add `getBatteryLevel` (https://github.com/rebeccahughes/react-native-device-info/pull/359)
+
 ### 0.17.4
 
 * Fix `getMACAddress` for Android > 6 (https://github.com/rebeccahughes/react-native-device-info/pull/349)

README.md

@@ -196,6 +196,7 @@ var DeviceInfo = require('react-native-device-info');
 | ------------------------------------------------- | ------------------- | :--: | :-----: | :-----: | ------ |
 | [getAPILevel()](#getapilevel)                     | `number`            |  ❌  |   ✅    |   ❌    | 0.12.0 |
 | [getApplicationName()](#getapplicationname)       | `string`            |  ✅  |   ✅    |   ✅    | 0.14.0 |
+| [getBatteryLevel()](#getbatterylevel)             | `Promise<number>`   |  ✅  |   ✅    |   ❌    | 0.18.0 |
 | [getBrand()](#getbrand)                           | `string`            |  ✅  |   ✅    |   ✅    | 0.9.3  |
 | [getBuildNumber()](#getbuildnumber)               | `string`            |  ✅  |   ✅    |   ✅    | ?      |
 | [getBundleId()](#getbundleid)                     | `string`            |  ✅  |   ✅    |   ✅    | ?      |
@@ -264,6 +265,24 @@ const appName = DeviceInfo.getApplicationName(); // "Learnium Mobile"
 
 ---
 
+### getBatteryLevel()
+
+Gets the battery level of the device as a float comprised between 0 and 1.
+
+**Examples**
+
+```js
+DeviceInfo.getBatteryLevel().then((batteryLevel) => {
+  // 0.759999
+});
+```
+
+**Notes**
+
+> Returns -1 on the iOS Simulator
+
+---
+
 ### getBrand()
 
 Gets the device brand.

RNDeviceInfo/RNDeviceInfo.m

@@ -304,4 +304,10 @@ RCT_EXPORT_METHOD(isPinOrFingerprintSet:(RCTResponseSenderBlock)callback)
     callback(@[[NSNumber numberWithBool:isPinOrFingerprintSet]]);
 }
 
+RCT_EXPORT_METHOD(getBatteryLevel:(RCTPromiseResolveBlock)resolve rejecter:(RCTPromiseRejectBlock)reject)
+{
+    float batteryLevel = [UIDevice currentDevice].batteryLevel;
+    resolve(@(batteryLevel));
+}
+
 @end

android/src/main/java/com/learnium/RNDeviceInfo/RNDeviceModule.java

@@ -4,6 +4,8 @@ import android.Manifest;
 import android.app.KeyguardManager;
 import android.bluetooth.BluetoothAdapter;
 import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
 import android.content.pm.PackageInfo;
 import android.content.pm.ApplicationInfo;
 import android.content.pm.PackageManager;
@@ -13,6 +15,7 @@ import android.net.wifi.WifiInfo;
 import android.os.Build;
 import android.os.Environment;
 import android.os.StatFs;
+import android.os.BatteryManager;
 import android.provider.Settings.Secure;
 import android.webkit.WebSettings;
 import android.telephony.TelephonyManager;
@@ -195,6 +198,15 @@ public class RNDeviceModule extends ReactContextBaseJavaModule {
     return null;
   }
 
+  @ReactMethod
+  public void getBatteryLevel(Promise p) {
+    Intent batteryIntent = this.reactContext.getApplicationContext().registerReceiver(null, new IntentFilter(Intent.ACTION_BATTERY_CHANGED));
+    int level = batteryIntent.getIntExtra(BatteryManager.EXTRA_LEVEL, -1);
+    int scale = batteryIntent.getIntExtra(BatteryManager.EXTRA_SCALE, -1);
+    float batteryLevel = level / (float) scale;
+    p.resolve(batteryLevel);
+  }
+
   @Override
   public @Nullable
   Map<String, Object> getConstants() {

deviceinfo.d.ts

@@ -37,4 +37,5 @@ export function getCarrier(): string;
 export function getTotalMemory(): number;
 export function getMaxMemory(): number;
 export function getTotalDiskCapacity(): number;
-export function getFreeDiskStorage(): number;
\ No newline at end of file
+export function getFreeDiskStorage(): number;
+export function getBatteryLevel(): Promise<number>;

deviceinfo.js

@@ -115,4 +115,7 @@ module.exports = {
   getFreeDiskStorage: function() {
     return RNDeviceInfo.freeDiskStorage;
   },
+  getBatteryLevel: function() {
+    return RNDeviceInfo.getBatteryLevel();
+  },
 };

deviceinfo.js.flow

@@ -38,4 +38,5 @@ declare module.exports: {
   getMaxMemory: () => number,
   getTotalDiskCapacity: () => number,
   getFreeDiskStorage: () => number,
+  getBatteryLevel: () => Promise<number>,
 };

web/index.js

@@ -37,4 +37,5 @@ module.exports = {
   maxMemory: 0,
   totalDiskCapacity: 0,
   freeDiskStorage: 0,
+  getBatteryLevel: () => Promise.resolve(0)
 };