1. <SPANstyle="FONT-FAMILY:'comicsansms',sans-serif;COLOR:#008080;FONT-SIZE:small">
3. @interfaceBackgroundTrackerViewController()
5. @end
7. @implementationBackgroundTrackerViewController
8. @synthesizelocationManager,startTrackingButton,alertLabel;
10. //开始跟踪
11. -(void)startTracking:(id)sender
12. {
13. [locationManagerstartUpdatingLocation];
14. }
17. -(void)start:(id)sender
18. {
19. //[locationManagerstartUpdatingLocation];
20. }
22. -(id)initWithNibName:(NSString*)nibNameOrNilbundle:(NSBundle*)nibBundleOrNil
23. {
24. self=[superinitWithNibName:nibNameOrNilbundle:nibBundleOrNil];
25. if(self){
26. //Custominitialization
27. }
28. returnself;
29. }
31. -(void)viewDidLoad
32. {
33. [superviewDidLoad];
34. //Doanyadditionalsetupafterloadingtheviewfromitsnib.
36. self.view.backgroundColor=[UIColorgrayColor];
39. self.startTrackingButton=[UIButtonbuttonWithType:UIButtonTypeRoundedRect];
40. startTrackingButton.frame=CGRectMake(0,200,100,50);
41. [startTrackingButtonaddTarget:selfaction:@selector(startTracking:)forControlEvents:UIControlEventTouchUpInside];
42. [startTrackingButtonsetTitle:@"startTracking"forState:UIControlStateNormal];
43. [self.viewaddSubview:startTrackingButton];
46. self.alertLabel=[[UILabelalloc]initWithFrame:CGRectMake(0,100,320,50)];
47. self.alertLabel.backgroundColor=[UIColororangeColor];
48. self.alertLabel.hidden=YES;
49. self.alertLabel.text=@"无法找到位置";
50. [self.viewaddSubview:alertLabel];
53. locationManager=[[CLLocationManageralloc]init];
54. [locationManagersetDelegate:self];
55. //Onlyapplieswheninforegroundotherwiseitisverysignificantchanges
56. [locationManagersetDesiredAccuracy:kCLLocationAccuracyBest];//要求的精确度
57. }
60. -(void)locationManager:(CLLocationManager*)managerdidUpdateToLocation:(CLLocation*)newLocationfromLocation:(CLLocation*)oldLocation{
61. CLLocationCoordinate2DcurrentCoordinates=newLocation.coordinate;
62. [alertLabelsetText:@"LocationHasbeenfound"];
63. [alertLabelsetHidden:NO];
64. NSLog(@"EnterednewLocationwiththecoordinatesLatitude:%fLongitude:%f",currentCoordinates.latitude,currentCoordinates.longitude);
65. }
66. -(void)locationManager:(CLLocationManager*)managerdidFailWithError:(NSError*)error{
67. NSLog(@"Unabletostartlocationmanager.Error:%@",[errordescription]);
68. [alertLabelsetHidden:NO];
69. }
72. -(void)didReceiveMemoryWarning
73. {
74. [superdidReceiveMemoryWarning];
75. //Disposeofanyresourcesthatcanberecreated.
76. }
77. </SPAN>

@interface BackgroundTrackerViewController ()

@end

@implementation BackgroundTrackerViewController
@synthesize locationManager,startTrackingButton,alertLabel;

//开始跟踪
- (void)startTracking:(id)sender
{
    [locationManager startUpdatingLocation]; 
}


-(void)start:(id)sender
{
//    [locationManager startUpdatingLocation]; 
}

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.
    
    self.view.backgroundColor=[UIColor grayColor];
    
    
    self.startTrackingButton=[UIButton buttonWithType:UIButtonTypeRoundedRect];
    startTrackingButton.frame=CGRectMake(0, 200, 100, 50);
    [startTrackingButton addTarget:self action:@selector(startTracking:) forControlEvents:UIControlEventTouchUpInside];
    [startTrackingButton setTitle:@"startTracking" forState:UIControlStateNormal];
    [self.view addSubview:startTrackingButton];
    
    
    self.alertLabel=[[UILabel alloc]initWithFrame:CGRectMake(0, 100, 320, 50)];
    self.alertLabel.backgroundColor=[UIColor orangeColor];
    self.alertLabel.hidden=YES;
    self.alertLabel.text=@"无法找到位置";
    [self.view addSubview:alertLabel];
    
    
    locationManager = [[CLLocationManager alloc] init];
    [locationManager setDelegate:self];
    //Only applies when in foreground otherwise it is very significant changes
    [locationManager setDesiredAccuracy:kCLLocationAccuracyBest];//要求的精确度
}


- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation {
    CLLocationCoordinate2D currentCoordinates = newLocation.coordinate;
    [alertLabel setText:@"Location Has been found"];
    [alertLabel setHidden:NO];
    NSLog(@"Entered new Location with the coordinates Latitude: %f Longitude: %f", currentCoordinates.latitude, currentCoordinates.longitude);
}
- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error {
    NSLog(@"Unable to start location manager. Error:%@", [error description]);
    [alertLabel setHidden:NO];
}


- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (void)applicationDidEnterBackground:(UIApplication *)application

Oc代码

1. <SPANstyle="FONT-FAMILY:'comicsansms',sans-serif;COLOR:#008080;FONT-SIZE:small">{
2. //Usethismethodtoreleasesharedresources,saveuserdata,invalidatetimers,andstoreenoughapplicationstateinformationtorestoreyourapplicationtoitscurrentstateincaseitisterminatedlater.
3. //Ifyourapplicationsupportsbackgroundexecution,thismethodiscalledinsteadofapplicationWillTerminate:whentheuserquits.
5. if([[UIDevicecurrentDevice]respondsToSelector:@selector(isMultitaskingSupported)])
6. {//CheckifouriOSversionsupportsmultitaskingI.EiOS4
7. if([[UIDevicecurrentDevice]isMultitaskingSupported])
8. {//Checkifdevicesupportsmulitasking
9. UIApplication*application=[UIApplicationsharedApplication];//Getthesharedapplicationinstance
11. __blockUIBackgroundTaskIdentifierbackground_task;//Createataskobject
13. background_task=[applicationbeginBackgroundTaskWithExpirationHandler:^{
14. /*
15. 当应用程序后台停留的时间为0时，会执行下面的操作（应用程序后台停留的时间为600s，可以通过backgroundTimeRemaining查看）
16. */
17. [applicationendBackgroundTask:background_task];//Tellthesystemthatwearedonewiththetasks
18. background_task=UIBackgroundTaskInvalid;//Setthetasktobeinvalid
20. //Systemwillbeshuttingdowntheappatanypointintimenow
21. }];
23. //Backgroundtasksrequireyoutouseasyncroustasks
25. dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT,0),^{
26. //Performyourtasksthatyourapplicationrequires
27. NSLog(@"timeremain:%f",application.backgroundTimeRemaining);
28. [applicationendBackgroundTask:background_task];//Endthetasksothesystemknowsthatyouaredonewithwhatyouneedtoperform
29. background_task=UIBackgroundTaskInvalid;//Invalidatethebackground_task
30. });
31. }
32. }
35. }
36. </SPAN>

作者：陈杭州

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