Background Fetch is a very simple plugin which will awaken an app in the background about every 15 minutes, providing a short period 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 — you will never receive an event faster than 15 minutes. The operating-system will automatically throttle the rate the background-fetch events occur based upon usage patterns. Eg: if user hasn't turned on their phone for a long period of time, fetch events will occur less frequently.
The plugin creates the object window.BackgroundFetch with the methods configure(success, fail, option), start(success, fail) and stop(success, fail).
$ cordova plugin add cordova-plugin-background-fetch <plugin name="cordova-plugin-background-fetch" source="npm" />The minimum interval in minutes to execute background fetch events. Defaults to 15 minutes. Note: Background-fetch events will never occur at a frequency higher than every 15 minutes. Apple uses a secret algorithm to adjust the frequency of fetch events, presumably based upon usage patterns of the app. Fetch events can occur less often than your configured minimumFetchInterval.
Set false to continue background-fetch events after user terminates the app. Default to true.
Set true to initiate background-fetch events when the device is rebooted. Defaults to false.
❗ NOTE: startOnBoot requires stopOnTerminate: false.
Set true to automatically relaunch the application (if it was terminated) — the application will launch to the foreground then immediately minimize. Defaults to false.
| Method Name | Arguments | Notes |
|---|---|---|
configure |
callbackFn, failureFn, {config} |
Configures the plugin's fetch callbackFn. This callback will fire each time an iOS background-fetch event occurs (typically every 15 min). The failureFn will be called if the device doesn't support background-fetch. |
finish |
none | 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. |
start |
successFn, failureFn |
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 |
stop |
successFn, failureFn |
Stop the background-fetch API from firing fetch events. Your callbackFn provided to #configure will no longer be executed. |
A full example could be:
onDeviceReady: function() {
var Fetcher = window.BackgroundFetch;
// Your background-fetch handler.
var fetchCallback = function() {
console.log('[js] BackgroundFetch event received');
// perform some asynchronous operation, such as an ajax request to your server.
$.get({
url: '/heartbeat.json',
callback: function(response) {
// process your response and whatnot.
////
// IMPORTANT: You MUST ALWAYS call the #finish method
// when your work is done to signal to the native code
// that your task is complete.
//
// If you neglect this, the OS can terminate your
// app for spending too long in the background in
// addition to assigning "battery blame" to your app.
//
Fetcher.finish(); // <-- Signal that your task is complete
}
});
}
var failureCallback = function(error) {
console.log('- BackgroundFetch failed', error);
};
Fetcher.configure(fetchCallback, failureCallback, {
minimumFetchInterval: 15, // <-- default is 15
stopOnTerminate: false, // <-- Android only
startOnBoot: true, // <-- Android only
forceReload: true // <-- Android only
});
}Implements performFetchWithCompletionHandler, firing a custom event subscribed-to in cordova plugin. Unfortunately, iOS automatically ceases background-fetch events when the user explicitly terminates the application or reboots the device.
Android implements background fetch using two different mechanisms, depending on the Android SDK version. Where the SDK version is >= LOLLIPOP, the new JobScheduler API is used. Otherwise, the old AlarmManager will be used.
Unlike iOS, the Android implementation can continue to operate after application terminate (stopOnTerminate: false) or device reboot (startOnBoot: true).
The MIT License
Copyright (c) 2013 Chris Scott, Transistor Software [email protected] http://transistorsoft.com
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