Implementation of Swift-background fetch data (Background fetch)

Here's how to get a program to request a background short run. But this extra time is limited after all. So, from IOS7, there are two ways to run tasks in the background: background fetching and background notifications.

1, backstage get introductionBackground access (Background Fetch) is designed for applications that require regular updates, such as weather applications, news clients, social networking applications, and so on. After the background acquisition is started, the application can be woken up in the background, getting the latest information in the background so that the information can be displayed immediately when the user moves the application to the foreground.
2, background access function openFirst in the selected item, in thecapabilities (features) tab, enable Background fetch in Background Modes (background mode) (background acquisition)

3, background get time interval settings(1) After the background acquisition function is turned on, you also need to use it in your code.the Setminimumbackgroundfetchinterval () method sets the time interval (in seconds) for the shortest wake-up program. But when the program will be awakened to get data, it is not controllable. This is decided by the system itself. (2) If you want to tell the call as frequently as possible, set it directly toUiapplicationbackgroundfetchintervalminimum.
4, using the sampleAfter the program is suspended, the Beijing time is automatically retrieved from the background, and a local notification is used to alert the user. (Note: To call Completionhandler after the background fetch executes to tell the system whether the data was successful)

import UIKit   @UIApplicationMain class AppDelegate: UIResponder, UIApplicationDelegate {           var window: UIWindow?           func application (application: UIApplication,         didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?)-> Bool {             // Enable notification             let settings = UIUserNotificationSettings (forTypes: [.Alert, .Badge, .Sound],                 categories: nil)             application.registerUserNotificationSettings (settings)             return true     }           func applicationWillResignActive (application: UIApplication) {     }           func applicationDidEnterBackground (application: UIApplication) {         // Although the minimum time for background acquisition is defined, iOS will wake up the program by its own best time, which we cannot control         // UIApplicationBackgroundFetchIntervalMinimum calls our Fetch method as often as possible         application.setMinimumBackgroundFetchInterval (UIApplicationBackgroundFetchIntervalMinimum)     }           func applicationWillEnterForeground (application: UIApplication) {     }           func applicationDidBecomeActive (application: UIApplication) {     }           func applicationWillTerminate (application: UIApplication) {     }           // Get data in the background     func application (application: UIApplication,         performFetchWithCompletionHandler completionHandler: (UIBackgroundFetchResult)-> Void) {             // Create NSURL object             let url: NSURL! = NSURL (string: "http://api.k780.com:88/?app=life.time&appkey=10003&sign=b59bc3ef6191eb9f747dd4e83c99f2a4&format=json")             // Create a request object             let request: NSURLRequest = NSURLRequest (URL: url)                           let session = NSURLSession.sharedSession ()                           let dataTask = session.dataTaskWithRequest (request,                 completionHandler: ((data, response, error)-> Void in                     if error! = nil {                         print (error? .code)                         print (error? .description)                                                   // Let the OS know that fetching data failed                         completionHandler (UIBackgroundFetchResult.Failed)                     } else {                         let str = NSString (data: data !, encoding: NSUTF8StringEncoding)                         print (str)                         // Clear all local pushes                         //UIApplication.sharedApplication (). CancelAllLocalNotifications ()                         // Create UILocalNotification for local message notification                         let localNotification = UILocalNotification ()                         // Push time (immediate push)                         localNotification.fireDate = NSDate (timeIntervalSinceNow: 0)                         //Time zone                         localNotification.timeZone = NSTimeZone.defaultTimeZone ()                         // Push content                         localNotification.alertBody = "Success in getting time: \ (str)"                         //sound                         localNotification.soundName = UILocalNotificationDefaultSoundName                         UIApplication.sharedApplication (). ScheduleLocalNotification (localNotification)                                                   // Let the OS know that new data has been obtained                         completionHandler (UIBackgroundFetchResult.NewData)                         //completionHandler(UIBackgroundFetchResult.NoData)                     }             }) as NSURLSessionTask                           // Use the resume method to start the task             dataTask.resume ()     } }

5, background get test

(1) Simulator test, as long as the selection of the Xcode menu bar debug under the simulate Background fetch can (2) Real machine debugging, if not attached to the computer sometimes wait a day before the background to get. It may take a few minutes for a computer to be attached. Http://www.hangge.com/blog/cache/detail_815.html

Implementation of Swift-background fetch data (Background fetch)