GPS 距离和速度未更新

Question

我有以下代码，用于获取用户行进的距离，并在两个标签中返回他们的速度。

.h 文件

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


    @interface pointToPointViewController : UIViewController<CLLocationManagerDelegate, UINavigationControllerDelegate>
    {
        CLLocationManager *locManager;
        CLLocationSpeed speed;
        NSTimer *timer;
        UILabel *speedText;
        UILabel *locationText;
        UILabel * distanceText;

        CLLocationSpeed currentSpeed;
        float fltDistanceTravelled;

    }

    @property (strong, nonatomic) IBOutlet UILabel *locationText;
    @property (strong, nonatomic) IBOutlet UILabel *distanceText;

    @property (nonatomic, retain) NSTimer *timer;
    -(float)getDistanceInKm:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation;
    @property (strong, nonatomic) IBOutlet UILabel *speedText;

.m 文件

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

@interface pointToPointViewController ()

@end

@implementation pointToPointViewController
@synthesize timer;
@synthesize speedText;
@synthesize distanceText;
@synthesize locationText;
-(void)startReadingLocation{
    [locManager startUpdatingLocation];
}


- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    CLLocationManager *locationManager=[[CLLocationManager alloc] init];
    locationManager.delegate=self;
    locationManager.desiredAccuracy=kCLLocationAccuracyBestForNavigation;
    [locationManager startUpdatingLocation];

    speedText = [[UILabel alloc]init];
    NSString *speedString = [NSString stringWithFormat:@"speed is %.2f", currentSpeed];
    speedText.text = speedString;


}

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



- (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];
    }
}

- (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;
    NSString *distancestring = [NSString stringWithFormat:@"%f.2",d];

    distanceText.text = distancestring;



}

当我使用“高速公路”位置选项运行应用程序时，没有任何文本字段正在更新，并且控制台没有提供任何信息（即行驶距离）

谁能确定我的代码中需要修复的地方？

提前致谢。

Answer 1

在你的方法中：

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

return 语句在文本设置之前，因此设置永远不会执行，为了解决这个问题，请将 return 语句移到方法的末尾。