iOS HTTP request while in background

问题:

It is possible to make HTTP async requests to PHP server while the app being in background? The app is a location based one, and should gather current location and send the coordinates to server every 5(or other value) minutes. Can I make the http posts to the server even the app is in background? I read lot of thoughts about this, but some of them told that can be done, others that can't be done.

Thanks,

Alex.

回答1:

It can be done but it is unreliable because you ask the OS for time to send something and it can accept or deny your request. This is what I have (stolen from somewhere on SO):

[...] //we get the new location from CLLocationManager somewhere here    
BOOL isInBackground = NO;
if ([UIApplication sharedApplication].applicationState == UIApplicationStateBackground)
{
    isInBackground = YES;
}
if (isInBackground)
{
    [self sendBackgroundLocationToServer:newLocation];
}


- (void) sendBackgroundLocationToServer: (CLLocation *) lc
{
    UIBackgroundTaskIdentifier bgTask = UIBackgroundTaskInvalid;
    bgTask = [[UIApplication sharedApplication]
         beginBackgroundTaskWithExpirationHandler:^{
             [[UIApplication sharedApplication] endBackgroundTask:bgTask];
    }];

    NSMutableDictionary *dictionary = [NSMutableDictionary dictionaryWithCapacity:2];
    [dictionary setObject:[NSNumber numberWithDouble:lc.coordinate.latitude] forKey:@"floLatitude"];
    [dictionary setObject:[NSNumber numberWithDouble:lc.coordinate.longitude] forKey:@"floLongitude"];
    // send to server with a synchronous request


    // AFTER ALL THE UPDATES, close the task
    if (bgTask != UIBackgroundTaskInvalid)
    {
        [[UIApplication sharedApplication] endBackgroundTask:bgTask];
    }
}

回答2:

These links will help you out...

iphone - Connecting to server in background