Core Location实现定位

2013/4/22记录：

注意：如非必要，不应该多次轮询位置信息i

使用时，可根据需要制定精度，通过仔细制定所需的绝对最低精度级别，可以纺织不必要的电池消耗。 

 

导入：CoreLocation.framework

导入头文件：#import <CoreLocation/CoreLocation.h>

实现CLLocationManagerDelegate协议

 

   self.locationManager= [[CLLocationManager alloc] init];    //位置管理器实例
    locationManager.delegate = self;    //设置委托
    locationManager.desiredAccuracy = kCLLocationAccuracyBest;  //设置请求制定精度级别，精度越高越耗电
    [locationManager startUpdatingLocation];    //启动

回调方法：

#pragma mark -
#pragma mark CLLocationManagerDelegate Methods
//当这个实施时下面那个就失效。
//- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations{
//
//}
- (void)locationManager:(CLLocationManager *)manager
    didUpdateToLocation:(CLLocation *)newLocation
           fromLocation:(CLLocation *)oldLocation {

    if (startingPoint == nil)   //如果没有开始坐标，选择刚定位到的坐标作为开始坐标
        self.startingPoint = newLocation;

    //纬度值
    NSString *latitudeString = [NSStringstringWithFormat:@"%g\u00B0",
                                newLocation.coordinate.latitude];   //“\u00B0”：角度符的Unicode表示形式
    latitudeLabel.text = latitudeString;

    //经度值
    NSString *longitudeString = [NSStringstringWithFormat:@"%g\u00B0",
                                 newLocation.coordinate.longitude];
    longitudeLabel.text = longitudeString;

    //以coordinate为中心的圆的半径
    NSString *horizontalAccuracyString = [NSStringstringWithFormat:@"%gm",
                                          newLocation.horizontalAccuracy];
    horizontalAccuracyLabel.text = horizontalAccuracyString;

    //海拔
    NSString *altitudeString = [NSStringstringWithFormat:@"%gm",
                                newLocation.altitude];
    altitudeLabel.text = altitudeString;

    //海拔方面的精度
    NSString *verticalAccuracyString = [NSStringstringWithFormat:@"%gm",
                                        newLocation.verticalAccuracy];
    verticalAccuracyLabel.text = verticalAccuracyString;

    //更新位置的时间戳
    NSLog(@"%lf\n",newLocation.timestamp.timeIntervalSince1970);

    //两位置距离
    CLLocationDistance distance = [newLocation
                                   distanceFromLocation:startingPoint];
    NSString *distanceString = [NSStringstringWithFormat:@"%gm", distance];
    distanceTraveledLabel.text = distanceString;

    //停止
    [self.locationManager stopUpdatingLocation];
}
- (void)locationManager:(CLLocationManager *)manager
       didFailWithError:(NSError *)error {
    NSString *errorType = (error.code == kCLErrorDenied) ?
    @"Access Denied" : @"Unknown Error";
    UIAlertView *alert = [[UIAlertViewalloc]
                          initWithTitle:@"Error getting Location"
                          message:errorType
                          delegate:nil
                          cancelButtonTitle:@"Okay"
                          otherButtonTitles:nil];
    [alert show];
}