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我正在构建一个在后台工作的iOS应用程序，并且每隔3分钟将用户的位置发布到服务器（因为这是iOS 7的最大后台执行时间）。 但是，有一个问题，后台服务在随机时间终止。所以有时它可以在后台运行2小时，有时可以运行7小时，然后3小时，随机运行。iOS 7的背景位置服务停止
下面的代码会产生错误。 我已经能够检测到当它将终止，那就是当[UIApplication sharedApplication] .backgroundTimeRemaining低于10秒。 任何人都可以指向某个方向，或解释为什么它终止？我的猜测是[self.locationManager startUpdatingLocation]不是100％安全的？ （以及使[UIApplication sharedApplication] .backgroundTimeRemaining unlimited？）的方法？）
这是我每3分钟在服务器上收到的“正常”日志;
iPhone 5：startUpdatingLocation前21:06:45 backgroundTimeRemaining：11.014648
iPhone 5：startUpdatingLocation之后21:06:45 backgroundTimeRemaining：999.000000
iPhone 5：stopUpdatingLocation前21时06分48秒backgroundTimeRemaining： 999.000000
iPhone 5：stopUpdatingLocation后，21时06分48秒backgroundTimeRemaining：999.000000
我感谢所有帮助我能！提前致谢！
代码：
#import "BetaLocationController.h"
#import "AppDelegate.h"
#import <Parse/Parse.h>
#import "CommunicationController.h"
@interface BetaLocationController() <CLLocationManagerDelegate>
@property UIBackgroundTaskIdentifier bgTask;
@property (strong, nonatomic) CLLocationManager *locationManager;
@property BOOL locationStarted;
@property (strong, nonatomic) CLLocation *myLocation;
@end
@implementation BetaLocationController
- (id)init
{
self = [super init];
if (self) {
self.locationManager = [[CLLocationManager alloc] init];
self.locationManager.delegate = self;
self.locationManager.pausesLocationUpdatesAutomatically = NO;
self.locationManager.activityType = CLActivityTypeOther;
self.locationManager.desiredAccuracy = kCLLocationAccuracyNearestTenMeters;
self.locationManager.distanceFilter = kCLDistanceFilterNone;
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(didEnterBackground:) name:UIApplicationDidEnterBackgroundNotification object:nil];
}
return self;
}
- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{
CLLocation* location = [locations lastObject];
self.myLocation = location;
// NSLog(@"Location: %f, %f", location.coordinate.longitude, location.coordinate.latitude);
}
- (void)didEnterBackground:(NSNotification *) notification
{
[self runBackgroundTask:10];
}
-(void)runBackgroundTask: (int) time{
//check if application is in background mode
if ([UIApplication sharedApplication].applicationState == UIApplicationStateBackground) {
//create UIBackgroundTaskIdentifier and create tackground task, which starts after time
__block UIBackgroundTaskIdentifier bgTask = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{
// [self runBackgroundTask:5];
[[UIApplication sharedApplication] endBackgroundTask:bgTask];
bgTask = UIBackgroundTaskInvalid;
}];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{
NSTimer *t = [NSTimer scheduledTimerWithTimeInterval:time target:self selector:@selector(startTrackingBg) userInfo:nil repeats:NO];
[[NSRunLoop currentRunLoop] addTimer:t forMode:NSDefaultRunLoopMode];
[[NSRunLoop currentRunLoop] run];
});
}
}
-(void)startTrackingBg{
[[UIApplication sharedApplication] cancelAllLocalNotifications];
UILocalNotification *localNotification = [[UILocalNotification alloc] init];
NSDate *now = [NSDate date];
localNotification.fireDate = now;
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"HHmm"];
int timeofDay = [[formatter stringFromDate:[NSDate date]] intValue];
localNotification.applicationIconBadgeNumber = timeofDay;
[[UIApplication sharedApplication] scheduleLocalNotification:localNotification];
//set default time
int time = 170;
//if locationManager is ON
if (self.locationStarted == TRUE) {
//Here I can detect the error
if([UIApplication sharedApplication].backgroundTimeRemaining < 10){
[CommunicationController logToParse:[NSString stringWithFormat:@"%@ : Detected error, trying to restart locationservice", [UIDevice currentDevice].name]];
}
//log
[CommunicationController logToParse:[NSString stringWithFormat:@"%@: %@ bgTime before stopUpdatingLocation: %f", [UIDevice currentDevice].name, [NSDate date], [self getBackgroundTime]]];
[self.locationManager stopUpdatingLocation];
self.locationStarted = FALSE;
//log
[CommunicationController logToParse:[NSString stringWithFormat:@"%@: %@ bgTime after stopUpdatingLocation: %f", [UIDevice currentDevice].name, [NSDate date], [self getBackgroundTime]]];
}else{
//start updating location
//log
[CommunicationController logToParse:[NSString stringWithFormat:@"%@: %@ bgTime before startUpdatingLocation: %f", [UIDevice currentDevice].name, [NSDate date], [self getBackgroundTime]]];
[self.locationManager startUpdatingLocation];
self.locationStarted = TRUE;
//Time how long the application will update your location
time = 3;
//log
[CommunicationController logToParse:[NSString stringWithFormat:@"%@: %@ bgTime after startUpdatingLocation: %f", [UIDevice currentDevice].name, [NSDate date], [self getBackgroundTime]]];
}
[self runBackgroundTask:time];
}
-(float)getBackgroundTime{
float bgTime = [[UIApplication sharedApplication] backgroundTimeRemaining];
//If bgtime is over 180, it returns unlimited. In iOS 7, only 3 minutes backgroundtime is available
return bgTime > 180 ? 999 : bgTime;
}
- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error
{
[CommunicationController logToParse:[NSString stringWithFormat:@"%@: %@ LocationManagerDidFail %@: %f", [UIDevice currentDevice].name, [NSDate date], error, [[UIApplication sharedApplication] backgroundTimeRemaining]]];
NSLog(@"Error in locationManager. It Failed: %@", error);
}
-(void)dealloc {
[CommunicationController logToParse:[NSString stringWithFormat:@"%@: %@ got dealloc'ed", [UIDevice currentDevice].name, [NSDate date]]];
NSLog(@"Dealloc in location manager is called");
}
@end
感谢您的回答！但是，我不认为这是一个资源问题，因为我正在使用两台只安装了应用程序并正在运行的测试电话 - 没有其他应用程序。 但是，我会尝试后台获取，因为我的理解我无法知道什么时候会被唤醒，而这取决于我自己的应用程序的用法？ – kbjeppesen
这是正确的。根据Apple的文档，如果你开始使用少量的时间，你的应用程序可能会启动得更多。您也可以在Xcode组织者中查找crashlog。 （连接iPhone，在Xcode中选择窗口 - >管理器，在左侧窗格中选择您的设备，然后单击设备日志） – EsbenB
我现在已经实现了后台抓取，它的工作原理非常好！功耗显着提高 - 我几乎无法检测到应用程序在后台运行！然而，正如我们已经讨论的那样，缺点是我无法控制什么时候会唤醒并联系我的服务器 - 但这是一个可以接受的折衷！感谢你的回答！ – kbjeppesen