ios 5 NSURLConnection并在待机模式下下载

问题描述 投票:0回答:1

我正在使用NSURLConnection从服务器下载内容(我正在使用iOS 5.0中的iPad应用程序)。我希望NSURLConnection继续下载,即使iPad进入待机状态。可能吗?

这是我的代码:

-(void)startDownload {

    UIDevice* device = [UIDevice currentDevice];
    BOOL backgroundSupported = NO;
    if ([device respondsToSelector:@selector(isMultitaskingSupported)])
        backgroundSupported = device.multitaskingSupported;    

    NSLog(@"\n\nbackgroundSupported= %d\n\n",backgroundSupported);

    dispatch_async(dispatch_get_main_queue(), ^ {

        NSURLRequest *req = [[NSURLRequest alloc] initWithURL:imageURL];
        NSURLConnection *conn = [[NSURLConnection alloc] initWithRequest:req delegate:self startImmediately:NO];
        [conn scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSRunLoopCommonModes];
        [conn start];

        if (conn) {
            NSMutableData *data = [[NSMutableData alloc] init];
            self.receivedData = data;

        }
        else {  ... }
    }) ;

}

谢谢!

ios download nsurlconnection standby dispatch-async
1个回答
1
投票

在终止之前,每个应用程序都可以在后台继续执行大约10分钟。只有某些应用可以继续在后台执行,例如音频/ gps /蓝牙等相关应用。您可以在Background Execution and Multitasking(左下方的App States和Multitasking部分)中找到更多信息。

以下代码示例来自app doc,可以帮助您开始使用,因此您的连接可以持续大约10分钟 -

- (void)applicationDidEnterBackground:(UIApplication *)application
{
    bgTask = [application beginBackgroundTaskWithExpirationHandler:^{
        // Clean up any unfinished task business by marking where you.
        // stopped or ending the task outright.
        [application endBackgroundTask:bgTask];
        bgTask = UIBackgroundTaskInvalid;
    }];

    // Start the long-running task and return immediately.
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

        // Do the work associated with the task, preferably in chunks.

        [application endBackgroundTask:bgTask];
        bgTask = UIBackgroundTaskInvalid;
    });
}
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