位置服务，如何在一段时间后（30秒）更新纬度，经度？
我从位置服务获取纬度，经度，高度，准确度，速度。
我想每30秒更新一次这些信息。 为此我使用了NSTimer：
[NSTimer scheduledTimerWithTimeInterval:30 target:self selector:@selector(locationUpdate:) userInfo:nil repeats:YES]; 我把它放在viewDidLoad方法中。 它第一次显示输出，但第二次，当计时器调用它时，显示这个错误：
2011-08-02 13:17:00.141 CoreLocationAssign[1120:207] This is location <__NSCFTimer: 0x4b200a0> 2011-08-02 13:17:00.142 CoreLocationAssign[1120:207] -[__NSCFTimer coordinate]: unrecognized selector sent to instance 0x4b200a0 2011-08-02 13:17:00.144 CoreLocationAssign[1120:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFTimer coordinate]: unrecognized selector sent to instance 0x4b200a0' *** Call stack at first throw:
代码如下：
MyCLController.h @implementation MyCLController @synthesize locationManager; @synthesize delegate; - (id) init{ if (self!=nil) { self.locationManager = [[[CLLocationManager alloc] init] autorelease]; self.locationManager.delegate = self; self.locationManager.desiredAccuracy = kCLLocationAccuracyBest; self.locationManager.distanceFilter = kCLDistanceFilterNone; [self.locationManager startUpdatingLocation]; } return self; } - (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation { //NSLog(@"Location: %@", [newLocation description]); [self.delegate locationUpdate:newLocation]; } - (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error { // NSLog(@"Error: %@", [error description]); [self.delegate locationError:error]; } - (void)dealloc { [self.locationManager release]; [super dealloc]; }
CoreLoactionController.h - (void)viewDidLoad { locationController = [[MyCLController alloc] init]; locationController.delegate = self; [locationController.locationManager startUpdatingLocation]; [NSTimer scheduledTimerWithTimeInterval:30 target:self selector:@selector(locationUpdate:) userInfo:nil repeats:YES]; [super viewDidLoad]; } - (void)locationUpdate:(CLLocation *)location { locationLable.text = [location description]; CLLocationCoordinate2D coordinate = [location coordinate]; NSLog(@"This is location %@",[location description]); NSLog(@"Lattitude = %@",[NSString stringWithFormat:@"%f", coordinate.latitude]); NSLog(@"Langitude = %@",[NSString stringWithFormat:@"%f", coordinate.longitude]); NSLog(@"Altitude = %@",[NSString stringWithFormat:@"%gm", location.altitude]); NSLog(@"horizontalAccuracy = %@",[NSString stringWithFormat:@"%gm", location.horizontalAccuracy]); NSLog(@"verticalAccuracy = %@",[NSString stringWithFormat:@"%gm", location.verticalAccuracy]); NSLog(@"Speed = %@",[NSString stringWithFormat:@"%gm", location.speed]); }
我可以怎样解决这个问题？ 我想每30秒更新一次地点
其实这里：
- (void)locationUpdate:(CLLocation *)location
你没有收到一个CLLocation *，而是一个NSTimer。 你应该使用userInfo来传送一个对象：
[NSTimer scheduledTimerWithTimeInterval:30 target:self selector:@selector(locationUpdate:) userInfo:location repeats:YES];
和
-(void)locationUpdate:(NSTimer*) timer{ //probably CLLocation *location = (CLLocation*)[timer userInfo]; //... }
有比使用计时器更好的解决scheme。 CoreLocation内置了用于延迟更新的function，与普通CoreLocation结合的定时器将摧毁手机电池。 尝试allowDeferredLocationUpdatesUntilDistanceTraveled：超时：
https ：/ / dev /
定时器的位置更新是可怕的电池食用者。
CoreLocation可以告诉你什么时候位置被改变，不需要轮询。 如果我走路的话，30秒太慢了，如果我的手机躺在我的床边不动了好几个小时，它就不必要地摧毁了电池。