第一步，开启后台模式，选中定位，选择project --> capabilities-->Backgorund Modes --> Location updates 如图：
第二步，在info.list 文件中添加如下配置：
允许 http 请求 ，ios 9 之后需要添加，便于向服务器发送请求
NSAppTransportSecurity
NSAllowsArbitraryLoads
添加定位权限，ios8之后需要添加，否则无法定位
NSLocationWhenInUseUsageDescription
YES
NSLocationAlwaysUsageDescription
YES
第三步，代码如下：
#import "ViewController.h"
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
self.view.backgroundColor = [UIColor whiteColor];
self.title = @"后台定位";
self.locationManager = [[CLLocationManager alloc] init];
self.locationManager.delegate = self;
[self.locationManager setDesiredAccuracy:kCLLocationAccuracyBest];
if([[UIDevice currentDevice].systemVersion floatValue] > 8)
{
/** 请求用户权限：分为：只在前台开启定位 /在后台也可定位， */
/** 只在前台开启定位 */
// [self.locationManager requestWhenInUseAuthorization];
/** 后台也可以定位 */
[self.locationManager requestAlwaysAuthorization];
}
if([[UIDevice currentDevice].systemVersion floatValue] > 9)
{
/** iOS9新特性：将允许出现这种场景：同一app中多个location manager：一些只能在前台定位，另一些可在后台定位（并可随时禁止其后台定位）。 */
[self.locationManager setAllowsBackgroundLocationUpdates:YES];
}
/** 开始定位 */
[self.locationManager startUpdatingLocation];
}
#pragma mark - 定位代理方法
- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{
CLLocation *loc = [locations objectAtIndex:0];
NSLog(@"经纬度 %f %f ",loc.coordinate.latitude,loc.coordinate.longitude);
NSURLSession *session = [NSURLSession sharedSession];
NSURLSessionDataTask *task = [session dataTaskWithRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://ac.ybjk.com/ua.php"]] completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
// NSLog(@"response %@",response);
NSString *result = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSLog(@"result %@",result);
}];
[task resume];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
@end
至此，完成后台实时定位功能，并向服务器发送请求成功