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我编写了一个简单的 iPhone 应用程序，它可以检索位置信息并简单地显示它们。我想在distanceTraveled每次位置变化时增加变量。我的问题是在方法locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations中，locations.count总是等于一。我以为每次调用该方法时都会向数组中添加一个元素，但似乎不是那样...

我正在模拟器中运行应用程序（我现在没有设备）。

这是我的代码：

// BIDViewController.h

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

@interface BIDViewController : UIViewController <CLLocationManagerDelegate>

@property (strong, nonatomic) CLLocationManager *locationManager;
@property (strong, nonatomic) CLLocation *startingPoint;

@property (strong, nonatomic) IBOutlet UILabel *latitudeLabel;
@property (strong, nonatomic) IBOutlet UILabel *longitudeLabel;
@property (strong, nonatomic) IBOutlet UILabel *horizontalAccuracyLabel;
@property (strong, nonatomic) IBOutlet UILabel *altitudeLabel;
@property (strong, nonatomic) IBOutlet UILabel *verticalAccuracyLabel;
@property (strong, nonatomic) IBOutlet UILabel *distanceTraveledLabel;

@end



// BIDViewController.m :

#import "BIDViewController.h"

@interface BIDViewController ()

@property (strong, nonatomic)CLLocation *currentLocation;
@property (strong, nonatomic)CLLocation *lastLocation;
@property CLLocationDistance distanceTraveled;

@end

@implementation BIDViewController

@synthesize latitudeLabel;
@synthesize locationManager;
@synthesize longitudeLabel;
@synthesize startingPoint;
@synthesize altitudeLabel;
@synthesize distanceTraveledLabel;
@synthesize horizontalAccuracyLabel;
@synthesize verticalAccuracyLabel;
@synthesize currentLocation;
@synthesize lastLocation;
@synthesize distanceTraveled;

- (void)viewDidLoad
{
    [super viewDidLoad];

    locationManager = [[CLLocationManager alloc] init];
    locationManager.delegate = self;
    locationManager.desiredAccuracy = kCLLocationAccuracyBest;
    //locationManager.distanceFilter = 10.0f;

    [locationManager startUpdatingLocation];
}

- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{
    if (startingPoint == nil) {
        startingPoint = [locations lastObject];
        NSLog(@"first time -- locations.count = %d", locations.count);
        distanceTraveled = 0;
        distanceTraveledLabel.text = @"0m";
    }
    else if (locations.count > 1) {
        NSLog(@"into the else if -- locations.count = %d", locations.count);
        lastLocation = locations[locations.count -2];
        distanceTraveled = distanceTraveled + [currentLocation distanceFromLocation:lastLocation];
        distanceTraveledLabel.text = [NSString stringWithFormat:@"%gm", distanceTraveled];
    }

    NSLog(@"locations.count = %d", locations.count);

    currentLocation = [locations lastObject];

    latitudeLabel.text =
        [NSString stringWithFormat:@"%g\u00B0", currentLocation.coordinate.latitude];
    longitudeLabel.text =
        [NSString stringWithFormat:@"%g\u00B0", currentLocation.coordinate.longitude];
    horizontalAccuracyLabel.text =
        [NSString stringWithFormat:@"%gm", currentLocation.horizontalAccuracy];
   verticalAccuracyLabel.text =
        [NSString stringWithFormat:@"%gm", currentLocation.verticalAccuracy];
    altitudeLabel.text =
        [NSString stringWithFormat:@"%gm", currentLocation.altitude];

}

- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error
{
    NSString *errorString = [[NSString alloc] init];

    switch (error.code) {
        case kCLErrorLocationUnknown:
            errorString = @"Location unknown";
            break;

        case kCLErrorDenied:
            errorString = @"Access denied";
            break;

        case kCLErrorNetwork:
            errorString = @"No network coverage";
            break;

        case kCLErrorDeferredAccuracyTooLow:
            errorString = @"Accuracy is too low to display";
            break;

        default:
            break;
    }

    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error getting location"
                                                    message:errorString
                                                   delegate:nil
                                          cancelButtonTitle:@"OK"
                                          otherButtonTitles:nil];
    [alert show];
}

@end

这是记录器的样子：

2012-11-21 11:28:34.882 WhereAmI[652:11c03] first time -- locations.count = 1
2012-11-21 11:28:34.897 WhereAmI[652:11c03] locations.count = 1
2012-11-21 11:28:35.835 WhereAmI[652:11c03] locations.count = 1
2012-11-21 11:28:36.835 WhereAmI[652:11c03] locations.count = 1
2012-11-21 11:28:37.836 WhereAmI[652:11c03] locations.count = 1
2012-11-21 11:28:38.836 WhereAmI[652:11c03] locations.count = 1
2012-11-21 11:28:39.837 WhereAmI[652:11c03] locations.count = 1
2012-11-21 11:28:40.837 WhereAmI[652:11c03] locations.count = 1
2012-11-21 11:28:41.838 WhereAmI[652:11c03] locations.count = 1
2012-11-21 11:28:42.839 WhereAmI[652:11c03] locations.count = 1

等等...

有什么建议吗？谢谢大家，一如既往，抱歉英语不好！

4

1 回答 1

2

模拟器不会返回多个位置，因为它使用您计算机的位置，因此您可以获得 Wi-Fi 的精度，仅此而已，除非您在运行时更改到其他地方的另一个 Wi-Fi 网络，否则它永远不会返回更高的精度/不同的位置。

如果您在移动的实际设备上进行测试，或者如果该设备首先为您提供蜂窝塔精度，然后是 Wi-Fi，然后是 GPS 精度，您将在阵列中收到多个位置。

希望这可以清除它。

于 2012-11-21T13:12:28.103 回答