iOS 不是典型的后台位置跟踪计时器问题 [英] iOS Not the typical background location tracking timer issue

问题描述

我正在开发一个在后台跟踪用户位置的示例应用程序，但我不想让定位服务始终处于启用状态，但我的计时器中的某些内容无法正常运行.

i'm developing a sample app that tracks the user's position in background, but i don't want to leave the location service always enabled, but something in my timer does not behave properly.

我的想法是，每隔 x 分钟，服务就会继续，当它有一个正确的新位置时，它会再次发布，现在设置为 10 秒，仅用于测试.(显着的 LocationChange 不是诀窍，不够准确)

My idea was that every x minutes, the service goes on, and when it have a correct new location it is released again, now is set to 10 seconds just for testing. (Significant LocationChange did not the trick, not accurated enough)

我搜索了很多(iOS 开发中心 + StackOverflow)并找到了新的"后台定位功能，它允许您在进入后台后 10 分钟内运行代码，使用 beginBackgroundTaskWithExpirationHandler、几个块和一个计时器.

I was searching a lot (iOS Dev center + StackOverflow) and found the "new" background location features, that allows you to run code over 10 minutes after going to background, using beginBackgroundTaskWithExpirationHandler, a few blocks, and a timer.

我将后台模式设置为位置，现在我认为我不需要处理后台时间的结束(首先我想每 15-20 秒获取一次位置)

I set the background mode to Location and by now i think i don't need to handle the end of the background time (first i want to get a location every 15-20 seconds)

代码运行良好，但是:

• 计时器有时会触发，有时不会.
• 当计时器触发时，至少需要 10 分钟.
• 操作系统中的一些随机操作(例如进入搜索桌面)似乎会估计触发计时器(不确定这一点，我不知道这是怎么可能的，但它确实存在......)

通过代码将是另一个问题.

And by over the code will be another qüestion.

appdelegates 的方法:

appdelegates's methods:

//applicationDidEnterBackground

- (void)applicationDidEnterBackground:(UIApplication *)application{

NSLog(@"to background");

UIApplication*    app = [UIApplication sharedApplication];

bgTask = [app beginBackgroundTaskWithExpirationHandler:^{
    [app 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.
    _triggertimer = nil;
    [self initTimer];

});
NSLog(@"backgroundTimeRemaining: %.0f", [[UIApplication sharedApplication] backgroundTimeRemaining]);}

//initTimer

- (void) initTimer{
NSLog(@"InitTimer ");


UIApplication *app = [UIApplication sharedApplication];

bgTask = [app beginBackgroundTaskWithExpirationHandler:^{



_triggertimer = [NSTimer scheduledTimerWithTimeInterval:10.0
                                                     target:self
                                                   selector:@selector(checkUpdates:)
                                                   userInfo:nil
                                                    repeats:YES];

[[NSRunLoop currentRunLoop] addTimer:_triggertimer forMode:NSDefaultRunLoopMode] ;
[[NSRunLoop currentRunLoop] run];

}];}

//检查更新

- (void)checkUpdates:(NSTimer *)timer{

NSLog(@"CheckUpdates ");

UIApplication*    app = [UIApplication sharedApplication];

if (nil == _locationManager) _locationManager = [[CLLocationManager alloc] init];

_locationManager.delegate = self;


_locationManager.distanceFilter = 10;
_locationManager.desiredAccuracy = kCLLocationAccuracyHundredMeters;

[_locationManager startUpdatingLocation];
[_locationManager startMonitoringSignificantLocationChanges];



double remaining = app.backgroundTimeRemaining;
NSLog(@"Reminaing %f", remaining);}

我尝试了很多方法来解决这个问题，也许我搞砸了或错过了什么……你看到了什么?也许是一些概念错误，我正在尝试向这些块介绍自己，但我还没有对它们进行域处理 ¬¬

I tried lots of thing to try to fix this and maybe i messed or missed something... What do you see? maybe some concept errors, i'm trying to introduce myself to the blocks and I don't domain them yet ¬¬

顺便说一句，为什么在使用 beginBackgroundTaskWithExpirationHandler 做任何事情之前我发现的所有代码都包含这个?

By the way,why all the codes i've found contains this before doing anything with beginBackgroundTaskWithExpirationHandler?

 bgTask = [app beginBackgroundTaskWithExpirationHandler:^{
    [app endBackgroundTask:bgTask];
    bgTask = UIBackgroundTaskInvalid;
}];

我以为这是为了拍摄那 600 秒的背景……但我不确定！

I thought that this is for taking that 600 seconds of background... but i'm not sure!

推荐答案

好的，问题是我调用了两次 beginBackgroundTaskWithExpirationHandler，一次在 ApplicationDidEnterBackground 中，另一次在 initTimer>...

Ok, the problem was that i was calling beginBackgroundTaskWithExpirationHandler twice, one in ApplicationDidEnterBackground and another one inside initTimer...

这篇关于iOS 不是典型的后台位置跟踪计时器问题的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！