feat(background-fetch): Adding Background Fetch requested in #990 (#1013)

* Adding Background Fetch (https://github.com/transistorsoft/cordova-plugin-background-fetch) requested in #990

* Adding BackgroundFetch to index

src/index.ts

@@ -13,6 +13,7 @@ import { AppRate } from './plugins/apprate';
 import { AppUpdate } from './plugins/app-update';
 import { AppVersion } from './plugins/appversion';
 import { Badge } from './plugins/badge';
+import { BackgroundFetch } from './plugins/background-fetch';
 import { BackgroundGeolocation } from './plugins/background-geolocation';
 import { BackgroundMode } from './plugins/backgroundmode';
 import { Backlight } from './plugins/backlight';
@@ -140,6 +141,7 @@ export * from './plugins/appodeal';
 export * from './plugins/apprate';
 export * from './plugins/app-update';
 export * from './plugins/appversion';
+export * from './plugins/background-fetch';
 export * from './plugins/background-geolocation';
 export * from './plugins/backgroundmode';
 export * from './plugins/backlight';
@@ -272,6 +274,7 @@ window['IonicNative'] = {
   AppVersion,
   Badge,
   BackgroundGeolocation,
+  BackgroundFetch,
   BackgroundMode,
   Backlight,
   BarcodeScanner,

src/plugins/background-fetch.ts

@@ -0,0 +1,107 @@
+import {Cordova, Plugin} from './plugin';
+
+declare var window;
+
+
+export interface BackgroundFetchConfig {
+
+  /**
+   * Set true to cease background-fetch from operating after user "closes" the app. Defaults to true.
+   */
+  stopOnTerminate?: boolean;
+}
+
+
+/**
+ * @name BackgroundFetch
+ * @description
+ * iOS Background Fetch Implementation. See: https://developer.apple.com/reference/uikit/uiapplication#1657399
+ * iOS Background Fetch is basically an API which wakes up your app about every 15 minutes (during the user's prime-time hours) and provides your app exactly 30s of background running-time. This plugin will execute your provided callbackFn whenever a background-fetch event occurs. There is no way to increase the rate which a fetch-event occurs and this plugin sets the rate to the most frequent possible value of UIApplicationBackgroundFetchIntervalMinimum -- iOS determines the rate automatically based upon device usage and time-of-day (ie: fetch-rate is about ~15min during prime-time hours; less frequently when the user is presumed to be sleeping, at 3am for example).
+ * For more detail, please see https://github.com/transistorsoft/cordova-plugin-background-fetch
+ *
+ * @usage
+ *
+ * ```typescript
+ * import { BackgroundFetch } from 'ionic-native';
+ *
+ *
+ * // When device is ready :
+ * platform.ready().then(() => {
+ *
+ *   let config = {
+ *     stopOnTerminate: false, // Set true to cease background-fetch from operating after user "closes" the app. Defaults to true.
+ *   };
+ *
+ *   BackgroundFetch.configure(() => {
+       console.log('[js] BackgroundFetch initiated');
+
+       // perform some ajax request to server here
+
+       You MUST called #finish so that native-side can signal completion of the background-thread to the os.
+       BackgroundFetch.finish();
+
+ *   }, (error) => {
+ *     console.log('- BackgroundFetch failed', error);
+ *   }, config);
+ *
+ * });
+ *
+ * // Start the background-fetch API. Your callbackFn provided to #configure will be executed each time a background-fetch event occurs. NOTE the #configure method automatically calls #start. You do not have to call this method after you #configure the plugin
+ * BackgroundFetch.start();
+ *
+ * // Stop the background-fetch API from firing fetch events. Your callbackFn provided to #configure will no longer be executed.
+ * BackgroundFetch.stop();
+ *
+ * ```
+ * @interfaces
+ * BackgroundFetchConfig
+ *
+ */
+@Plugin({
+  pluginName: 'BackgroundFetch',
+  plugin: 'cordova-plugin-background-fetch',
+  pluginRef: 'BackgroundFetch',
+  repo: 'https://github.com/transistorsoft/cordova-plugin-background-fetch',
+  platforms: ['iOS']
+})
+export class BackgroundFetch {
+
+
+  /**
+   * Configures the plugin's fetch callbackFn
+   *
+   * @param {Function} callbackFn This callback will fire each time an iOS background-fetch event occurs (typically every 15 min).
+   * @param {Function} errorCallback The failureFn will be called if the device doesn't support background-fetch.
+   * @param {BackgroundFetchConfig} config Configuration for plugin
+   * @return Location object, which tries to mimic w3c Coordinates interface.
+   * See http://dev.w3.org/geo/api/spec-source.html#coordinates_interface
+   * Callback to be executed every time a geolocation is recorded in the background.
+   */
+  @Cordova({
+    sync: true
+  })
+  static configure(callbackFn: Function, errorCallback: Function, config: BackgroundFetchConfig): any { return; }
+
+
+
+  /**
+   * Start the background-fetch API.
+   * Your callbackFn provided to #configure will be executed each time a background-fetch event occurs. NOTE the #configure method automatically calls #start. You do not have to call this method after you #configure the plugin
+   * @returns {Promise<any>}
+   */
+  @Cordova()
+  static start(): Promise<any> { return; }
+
+  /**
+   * Stop the background-fetch API from firing fetch events. Your callbackFn provided to #configure will no longer be executed.
+   * @returns {Promise<any>}
+   */
+  @Cordova()
+  static stop(): Promise<any> { return; }
+
+  /**
+   * You MUST call this method in your fetch callbackFn provided to #configure in order to signal to iOS that your fetch action is complete. iOS provides only 30s of background-time for a fetch-event -- if you exceed this 30s, iOS will kill your app.
+   */
+  @Cordova()
+  static finish() { }
+}