设备从休眠状态唤醒后后台位置更新未恢复

Question

我遇到一个问题，即应用正在注册后台位置更新，直到 设备 休眠，但在设备从休眠状态恢复后，位置更新不会恢复。

该应用程序非常简单，因为它可以测量位置更新对电池寿命的影响。

我使用单视图应用程序模板创建了应用程序，并且：

• 将下面发布的代码添加到应用程序委托（仅此而已，没有其他 代码）
• 添加了位置更新后台模式
• 添加了 coreLocation.framework

当我启动应用程序然后将其移至后台时，didUpdateLocations: 继续被连续调用大约 15-20 分钟，并且 getDataUsage() 每隔几秒执行一次。

然后大约 15-20 分钟后，设备进入休眠状态（我在 Organizer 的控制台上监控活动）。 但是，在唤醒设备后，该应用永远不会收到任何 didUpdateLocations: 调用。

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.locationManager = [[CLLocationManager alloc] init];
    self.locationManager.delegate = self;
    self.timeThatDataMonitoringStarted = [NSDate date];
    self.initialDataValuesSet = NO;

    CLLocationDegrees degreesFilter = 0.1;
    [self.locationManager setHeadingFilter: degreesFilter];
    self.locationManager.desiredAccuracy = kCLLocationAccuracyBest;
    self.locationManager.distanceFilter = 10;
    [self.locationManager startUpdatingLocation];

    [self getDataUsage];

    return YES;
}

- (void) locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{
    NSLog(@"******************** LOCATION didUpdateLocations ***************");
    static NSDate* previousDate;
    static int count = 0;
    if (previousDate)
    {
        NSTimeInterval timeInterval = [[NSDate date] timeIntervalSinceDate:previousDate];
        NSLog(@" LOCATION: count: %d time since last update: %f", ++count, timeInterval);
    }
    previousDate = [NSDate date];
}

- (void) getDataUsage
{
    NSTimeInterval elapsedTime = [[NSDate date] timeIntervalSinceDate: self.timeThatDataMonitoringStarted];
    NSLog(@"********* GETTING DATA USAGE. Elapsed time: %f **************",elapsedTime);
    NSArray *data = [self getDataCounters];

    NSNumber *wifiSentSinceBoot = (NSNumber*)data[0];
    NSNumber *wifiReceivedSinceBoot = (NSNumber*)data[1];
    NSNumber *wwanSentSinceBoot = (NSNumber*)data[2];
    NSNumber *wwanReceivedSinceBoot = (NSNumber*)data[3];

    int wifiSentSinceBootAsInt      = [wifiSentSinceBoot intValue];
    int wifiReceivedSinceBootAsInt  = [wifiReceivedSinceBoot intValue];
    int wWanSentSinceBootAsInt      = [wwanSentSinceBoot intValue];
    int wWanReceivedSinceBootAsInt  = [wwanReceivedSinceBoot intValue];

    static int initialWifiSent;
    static int initialWifiReceived;
    static int initialWWanSent;
    static int initialWWanReceived;
    if (!self.initialDataValuesSet)
    {
        self.initialDataValuesSet    = YES;
        initialWifiSent     = wifiSentSinceBootAsInt;
        initialWifiReceived = wifiReceivedSinceBootAsInt;
        initialWWanSent     = wWanSentSinceBootAsInt;
        initialWWanReceived = wWanReceivedSinceBootAsInt;
    }

    int wifiSentSinceLastRetrieval     = wifiSentSinceBootAsInt - initialWifiSent;
    int wifiReceivedSinceLastRetrieval = wifiReceivedSinceBootAsInt - initialWifiReceived;
    int wWanSentSinceLastRetrieval     = wWanSentSinceBootAsInt - initialWWanSent;
    int wWanReceivedSinceLastRetrieval  = wWanReceivedSinceBootAsInt - initialWWanReceived;

    uint dataUsed = wifiSentSinceLastRetrieval + wifiReceivedSinceLastRetrieval + wWanSentSinceLastRetrieval + wWanReceivedSinceLastRetrieval;
    NSLog(@"Total data: %d", dataUsed);
    [self performSelector:@selector(getDataUsage) withObject:nil afterDelay:3];
}


- (NSArray *) getDataCounters
{
    BOOL   success;
    struct ifaddrs *addrs;
    const struct ifaddrs *cursor;
    const struct if_data *networkStatisc;

    int WiFiSent = 0;
    int WiFiReceived = 0;
    int WWANSent = 0;
    int WWANReceived = 0;

    NSString *name=[[NSString alloc]init];

    success = getifaddrs(&addrs) == 0;
    if (success)
    {
        cursor = addrs;
        while (cursor != NULL)
        {
            name=[NSString stringWithFormat:@"%s",cursor->ifa_name];
            //   NSLog(@"ifa_name %s == %@\n", cursor->ifa_name,name);
            // names of interfaces: en0 is WiFi ,pdp_ip0 is WWAN

            if (cursor->ifa_addr->sa_family == AF_LINK)
            {
                if ([name hasPrefix:@"en"])
                {
                    networkStatisc = (const struct if_data *) cursor->ifa_data;
                    WiFiSent+=networkStatisc->ifi_obytes;
                    WiFiReceived+=networkStatisc->ifi_ibytes;
                    //  NSLog(@"WiFiSent %d ==%d",WiFiSent,networkStatisc->ifi_obytes);
                    //  NSLog(@"WiFiReceived %d ==%d",WiFiReceived,networkStatisc->ifi_ibytes);
                }

                if ([name hasPrefix:@"pdp_ip"])
                {
                    networkStatisc = (const struct if_data *) cursor->ifa_data;
                    WWANSent+=networkStatisc->ifi_obytes;
                    WWANReceived+=networkStatisc->ifi_ibytes;
                    //  NSLog(@"WWANSent %d ==%d",WWANSent,networkStatisc->ifi_obytes);
                    //  NSLog(@"WWANReceived %d ==%d",WWANReceived,networkStatisc->ifi_ibytes);
                }
            }

            cursor = cursor->ifa_next;
        }

        freeifaddrs(addrs);
    }

    return [NSArray arrayWithObjects:[NSNumber numberWithInt:WiFiSent], [NSNumber numberWithInt:WiFiReceived],[NSNumber numberWithInt:WWANSent],[NSNumber numberWithInt:WWANReceived], nil];
}

请注意，我使用的“休眠”一词不是指应用程序状态，而是指设备状态。如果您在 Organizer 的控制台中观察到设备活动，那么一段时间后，整个设备就会开始关闭。我称之为休眠是因为我不知道实际的 iOS 术语是什么，而且休眠也不是指自动锁定和屏幕休眠。之后这是一个单独的活动，我假设电话和 GPS 芯片等正在断电。 无论如何，在达到这个“休眠”阶段之后，如果你在设备上恢复活动，我就没有得到 didUpdateLocations。

Answer 1

您需要从 App 委托方法中移动您的 getDataUsage 方法调用：

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

致 CLLocationManager 委托：

- (void) locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations

由于每次发生位置更新（调用上述委托），您的 getDataUsage 都会被调用。

尝试使用 performSelector 使用伪“For 循环”是不好的设计，并且会在应用程序处于后台模式时导致不可预知的结果。所以你需要删除那一行：

[self performSelector:@selector(getDataUsage) withObject:nil afterDelay:3];

如果您打算让应用在后台运行，我还会确保该应用已注册为后台模式。

我还会在此处的答案中查看更多详细信息： iOS7 Core Location not updating