实战iPhone GPS定位系统

核心提示：lm.distanceFilter = 1000.0f;[lm startUpdatingLocation];mapView = [[MKMapView alloc] initWithFrame:self.view.bounds];mapView.mapType = MKMapTypeHybrid;}- (void)

lm.distanceFilter = 1000.0f;

[lm startUpdatingLocation];

mapView = [[MKMapView alloc] initWithFrame:self.view.bounds];

mapView.mapType = MKMapTypeHybrid;

}

- (void) locationManager: (CLLocationManager *) manager

didUpdateToLocation: (CLLocation *) newLocation

fromLocation: (CLLocation *) oldLocation{

NSString *lat = [[NSString alloc] initWithFormat:@"%g",

newLocation.coordinate.latitude];

latitudeTextField.text = lat;

NSString *lng = [[NSString alloc] initWithFormat:@"%g",

newLocation.coordinate.longitude];

longitudeTextField.text = lng;

NSString *acc = [[NSString alloc] initWithFormat:@"%g",

newLocation.horizontalAccuracy];

accuracyTextField.text = acc;

[acc release];

[lat release];

[lng release];

MKCoordinateSpan span;

span.latitudeDelta=.005;

span.longitudeDelta=.005;

MKCoordinateRegion region;

region.center = newLocation.coordinate;

region.span=span;

[mapView setRegion:region animated:TRUE];

}

- (void) dealloc{

[mapView release];

[lm release];

[latitudeTextField release];

[longitudeTextField release];

[accuracyTextField release];

[super dealloc];

}

代码解释：

l 当视图载入时创建一个MKMapView类的实例，设置显示的地图类型。

l 当用户点击View Map按钮时，在当前视图上增加mapView对象。

l 当位置信息得到更新时，使用mapView对象的setRegion:方法放大地图。

在iPhone模拟器中按Command-r测试该程序，点击View Map按钮将会显示一个包含位置管理器返回位置的地图。如图4所示。

图 4 地图位置：通过定位内核框架显示地图位置