如何计算用户从当前位置到iPhone特定位置的当前速度和平均速度？

Question

我有一个地图应用程序.当一个人从当前位置旅行到特定位置时,我想计算该人所覆盖的距离,该人的当前速度,该人的平均速度.

Answer 1

使用以下方法获得英里或公里的距离.你必须在头文件中声明计时器来合成它.

//SpeedViewController.h
#import <UIKit/UIKit.h>
#import <CoreLocation/CoreLocation.h>
#import <MobileCoreServices/UTCoreTypes.h>

@interface SpeedViewController : UIViewController <CLLocationManagerDelegate,UINavigationControllerDelegate>
{
    CLLocationManager *locManager;
    CLLocationSpeed speed;
    NSTimer *timer;

    CLLocationSpeed currentSpeed;
    float fltDistanceTravelled; 
}

@property (nonatomic,retain) NSTimer *timer;

-(float)getDistanceInKm:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation;
-(float)getDistanceInMiles:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation;

@end

//SpeedViewController.h
#import "SpeedViewController.h"
#define kRequiredAccuracy 500.0 //meters
#define kMaxAge 10.0 //seconds
#define M_PI   3.14159265358979323846264338327950288   /* pi */


@implementation SpeedViewController

@synthesize timer;
- (void)startReadingLocation {
    [locManager startUpdatingLocation];
}
// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad {
    [super viewDidLoad];

    CLLocationManager *locationManager=[[CLLocationManager alloc] init];
    locationManager.delegate=self;
    locationManager.desiredAccuracy=kCLLocationAccuracyBestForNavigation;
    [locationManager startUpdatingLocation];
}
- (void)didReceiveMemoryWarning {
    // Releases the view if it doesn't have a superview.
    [super didReceiveMemoryWarning];

    // Release any cached data, images, etc. that aren't in use.
}

- (void)viewDidUnload {
    [super viewDidUnload];
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}


- (void)dealloc {
    [super dealloc];
}

- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation 
{
    NSLog(@"new->%d old->%d",(newLocation==NULL),(oldLocation==NULL));

    if(newLocation && oldLocation)
    {
        fltDistanceTravelled +=[self getDistanceInKm:newLocation fromLocation:oldLocation];
    }
}

//this is a wrapper method to fit the required selector signature
- (void)timeIntervalEnded:(NSTimer*)timer {
    fltDistanceTravelled=0;
    [self startReadingLocation];
}


-(float)getDistanceInKm:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation
{
    float lat1,lon1,lat2,lon2;

    lat1 = newLocation.coordinate.latitude  * M_PI / 180;
    lon1 = newLocation.coordinate.longitude * M_PI / 180;

    lat2 = oldLocation.coordinate.latitude  * M_PI / 180;   
    lon2 = oldLocation.coordinate.longitude * M_PI / 180;

    float R = 6371; // km
    float dLat = lat2-lat1;
    float dLon = lon2-lon1; 

    float a = sin(dLat/2) * sin(dLat/2) + cos(lat1) * cos(lat2) * sin(dLon/2) * sin(dLon/2); 
    float c = 2 * atan2(sqrt(a), sqrt(1-a)); 
    float d = R * c;

    NSLog(@"Kms-->%f",d);

    return d;
}

-(float)getDistanceInMiles:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation
{
    float lat1,lon1,lat2,lon2;

    lat1 = newLocation.coordinate.latitude  * M_PI / 180;
    lon1 = newLocation.coordinate.longitude * M_PI / 180;

    lat2 = oldLocation.coordinate.latitude  * M_PI / 180;   
    lon2 = oldLocation.coordinate.longitude * M_PI / 180;

    float R = 3963; // km
    float dLat = lat2-lat1;
    float dLon = lon2-lon1; 

    float a = sin(dLat/2) * sin(dLat/2) + cos(lat1) * cos(lat2) * sin(dLon/2) * sin(dLon/2); 
    float c = 2 * atan2(sqrt(a), sqrt(1-a)); 
    float d = R * c;

    NSLog(@"Miles-->%f",d);

    return d;
}

@end

我没有在设备上测试过这个,但从逻辑上说它应该可行.