我正试图实施这篇文章中提供的建议。
不幸的是,这些步骤对我来说并不清晰。我尝试实现这些建议,但即使在我启动和停止locationServices之后,backgroundTimeRemaining仍然会减少。 这是我开发它的方式:
- (void)applicationDidEnterBackground:(UIApplication *)application {
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.
self.timer = nil;
[self initTimer];
});
}
初始化计时器:
- (void)initTimer {
// Create the location manager if this object does not
// already have one.
if (nil == self.locationManager)
self.locationManager = [[CLLocationManager alloc] init];
self.locationManager.delegate = self;
[self.locationManager startMonitoringSignificantLocationChanges];
if (self.timer == nil) {
self.timer = [NSTimer scheduledTimerWithTimeInterval:0.3
target:self
selector:@selector(checkUpdates:)
userInfo:nil
repeats:YES];
}
}
检查更新:
- (void)checkUpdates:(NSTimer *)timer{
UIApplication* app = [UIApplication sharedApplication];
double remaining = app.backgroundTimeRemaining;
if(remaining < 580.0) {
[self.locationManager startUpdatingLocation];
[self.locationManager stopUpdatingLocation];
[self.locationManager startMonitoringSignificantLocationChanges];
}
DbgLog(@"Reminaing %f", app.backgroundTimeRemaining);
}
有人能指出我的代码可能有什么问题吗?initTimer和checkUpdates都在后台执行时调用,但只有在执行时间(约为10分钟)内才会被调用。我希望这个应用程序可以每n分钟更新一次位置,一直更新下去。我的应用程序的UIBackgroundModes设置为location。
更新: 现在我在didUpdateToLocation和didFailWithError上重置了计时器,但backgroundTimeRemaining仍然在减少:
- (void)locationManager:(CLLocationManager *)manager
didUpdateToLocation:(CLLocation *)newLocation
fromLocation:(CLLocation *)oldLocation {
NSLog(@"Did Update Location = %f / %f", [newLocation coordinate].latitude, [newLocation coordinate].longitude);
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.
[self initTimer];
});
}
- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error {
[self.locationManager stopUpdatingLocation];
UIApplication* app = [UIApplication sharedApplication];
bgTask = [app beginBackgroundTaskWithExpirationHandler:^{
[app endBackgroundTask:bgTask];
bgTask = UIBackgroundTaskInvalid;
}];
// Start the long-running task and return immediately.
[self initTimer];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
// Do the work associated with the task.
});
}
我还在使定时器失效:
- (void)checkUpdates:(NSTimer *)timer{
UIApplication* app = [UIApplication sharedApplication];
double remaining = app.backgroundTimeRemaining;
if(remaining < 580.0 && remaining > 570.0) {
[self.timer invalidate];
self.timer = nil;
[self.locationManager startUpdatingLocation];
[self.locationManager stopUpdatingLocation];
}
DbgLog(@"*************************Checking for updates!!!!!!!!!!! Reminaing %f", app.backgroundTimeRemaining);
}