ios app退到后台还能继续把未完成的线程走完

在- (BOOL)application:(UIApplication*)application didFinishLaunchingWithOptions:(NSDictionary*)launchOptions方法中增加一行代码

[self rjxContinuedLocationManager]; //保证app不被系统kill掉

在appDelegate.m中增加以下方法

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

    // 可以在后台继续运行

    UIApplication*   app = [UIApplication sharedApplication];

    __block    UIBackgroundTaskIdentifier bgTask;

    bgTask = [app beginBackgroundTaskWithExpirationHandler:^{

        dispatch_async(dispatch_get_main_queue(), ^{

            if (bgTask != UIBackgroundTaskInvalid)

            {

                bgTask = UIBackgroundTaskInvalid;

            }

        });

    }];

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

        dispatch_async(dispatch_get_main_queue(), ^{

            if (bgTask != UIBackgroundTaskInvalid)

            {

                bgTask = UIBackgroundTaskInvalid;

            }

        });

    });

// 以上只是在app退到后台可以把未完成的线程走完，如果想保持长时间不被系统挂起，可以增加一个定位功能，不停的在后端定位

    if (self.keepActive) {

        [self.locationManager startUpdatingLocation];

    }

    //    [self endUploadTimer];

}

 应用进入后台执行定位 保证进程不被系统kill

 */

-(void)rjxContinuedLocationManager

{

    //1.创建定位管理对象

    self.locationManager = [[CLLocationManager alloc] init];

    //2.设置属性 distanceFilter、desiredAccuracy

    [self.locationManager setDistanceFilter:kCLDistanceFilterNone];//实时更新定位位置

    [self.locationManager setDesiredAccuracy:kCLLocationAccuracyBest];//定位精确度

    //该模式是抵抗程序在后台被杀，申明不能够被暂停

    self.locationManager.pausesLocationUpdatesAutomatically = NO;

    if([self.locationManager respondsToSelector:@selector(requestAlwaysAuthorization)]){

        [self.locationManager requestAlwaysAuthorization];

    }

    if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 9) {

        self.locationManager.allowsBackgroundLocationUpdates = YES;

    }

}

// 当你的程序将要被挂起，会调用改方法

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

    /** 应用进入后台执行定位 保证进程不被系统kill */

    [[UIApplication sharedApplication] beginReceivingRemoteControlEvents];

    if (self.keepActive) {

        [self.locationManager startUpdatingLocation];

    }

}

- (void)applicationDidBecomeActive:(UIApplication *)application

{

    application.applicationIconBadgeNumber = 0;

    [self.locationManager stopUpdatingLocation];

}