ios背景更新和下载

ios背景更新和下载

by 吴雪莹

- (BOOL)application:(UIApplication
*)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

    [application setMinimumBackgroundFetchInterval:UIApplicationBackgroundFetchIntervalMinimum];

    NSLog(@"Launched in background %d",UIApplicationStateBackground
== application.applicationState);

    return
YES;

}

// 1.利用Background Fetch

- (void)application:(UIApplication
*)application performFetchWithCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler
{

    NSURLSessionConfiguration *sessionConfiguration = [NSURLSessionConfiguration
defaultSessionConfiguration];

    NSURLSession *session = [NSURLSession
sessionWithConfiguration:sessionConfiguration];

    NSURL *url = [[NSURL
alloc]
initWithString:@"http://127.0.0.1/data.json"];

    NSURLSessionDataTask *task = [session 
dataTaskWithURL:url

                                         completionHandler:^(NSData
*data, NSURLResponse *response,
NSError *error) {

                                             if (error) {

                                                 completionHandler(UIBackgroundFetchResultFailed);

                                                 return;

                                             }

                                             completionHandler(UIBackgroundFetchResultNewData);

                                         }];

    [task resume];

}

// 2.利用Remote Notification

/*

 推送的内容

 {

 "aps" : {

 "content-available" : 1

 },

 "content-id" : 42

 }

 */

- (void)application:(UIApplication
*)application

didReceiveRemoteNotification:(NSDictionary *)userInfo

fetchCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler

{

    NSLog(@"Received remote notification with userInfo
%@", userInfo);

   

    NSNumber *contentID = userInfo[@"content-id"];

    NSString *downloadURLString = [NSString
stringWithFormat:@"http://yourserver.com/downloads/%d.mp3",
[contentID intValue]];

    NSURL* downloadURL = [NSURL
URLWithString:downloadURLString];

   

    NSURLRequest *request = [NSURLRequest
requestWithURL:downloadURL];

    NSURLSessionDownloadTask *task = [[self
backgroundURLSession]
downloadTaskWithRequest:request];

    task.taskDescription = [NSString
stringWithFormat:@"Podcast Episode %d",
[contentID intValue]];

    [task resume];

    completionHandler(UIBackgroundFetchResultNewData);

}



- (NSURLSession *)backgroundURLSession

{

    static
NSURLSession *session =
nil;

    static
dispatch_once_t onceToken;

    dispatch_once(&onceToken, ^{

        NSString *identifier =
@"io.objc.backgroundTransferExample";

        NSURLSessionConfiguration* sessionConfig = [NSURLSessionConfiguration
backgroundSessionConfiguration:identifier];

        session = [NSURLSession
sessionWithConfiguration:sessionConfig

                                                delegate:self

                                           delegateQueue:[NSOperationQueue
mainQueue]];

    });

    return session;

}

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