#Background Transfer - Adobe AIR Native Extension for iOS

This AIR Native Extension provides AS3 API to use iOS Background Transfer Service for downloading files in Adobe AIR application.

Starting from iOS7, with Background Transfer Service:

• downloads and uploads are managed by iOS;
• the transfer continues even when the user sends the app to the background (e.g. switches to another app);
• there's no time limit for download/upload;
• if the app crashes during the download/upload, the retransmission will start automatically when the app is launched;

Read more about NSURLSession in Apple documentation: https://developer.apple.com/library/IOs/documentation/Foundation/Reference/NSURLSession_class/index.html Read more about multitasking in iOS: NSURLSession and Background Transfer Service

Usage

Initialize BackgroundTransfer object:

BackgroundTransfer.instance.initializeSession(SESSION_ID);

downloadTask = BackgroundTransfer.instance.createDownloadTask(sessionID, remoteURL, localPath);
downloadTask.addEventListener(ProgressEvent.PROGRESS, onDownloadTaskProgress, false, 0, true);
downloadTask.addEventListener(Event.COMPLETE, onDownloadTaskCompleted, false, 0, true);
downloadTask.addEventListener(ErrorEvent.ERROR, onDownloadTaskError, false, 0, true);
downloadTask.resume();

To continue download tasks that were interrupted (for instance, due to app crash) implement initialization event:

BackgroundTransfer.instance.addEventListener(BTSessionInitializedEvent.INITIALIZED, onBackgroundSessionInitialized, false, 0, true);

private function onBackgroundSessionInitialized(event:BTSessionInitializedEvent):void {
    for each (var runningTask:BTDownloadTask in event.runningTasks) {
        // continue tasks
    }
}

Run the demo project for more implementation details.

Limitations

Upload tasks are not supported and currently I'm not working on it. Pull requests are welcome :). There's no support for Android platform.

Building

Requirements – Adobe Air SDK 4.0 or later, Xcode, iOS SDK 7.0 or later

Add the FlashRuntimeExtensions.h file from the Adobe AIR SDK to the ios/BackgroundTransferANE/BackgroundTransferANE folder in the project. Update the build/ant-build.config file in the build folder to match your Adobe AIR SDK setup. Run the ant build script ant-build.xml. This will compile and package the ANE. Binary files will be saved into bin/ folder.

Changelog

version 1.1

• file can be downloaded to any possible location on iOS (instead of limiting the location to Documents folder);
• updated background session setup to not use deprecated APIs;

##License

Default (not native) implementation of this ANE uses GreenSock LoaderMax for downloading files. greensock.swc library is subject to its own license. Please follow https://greensock.com/licensing/ for more details.

---

The MIT License (MIT)

Copyright (c) 2014 Maciek Grzybowski

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.