ios - 行进距离值不准确

Question

刚开始使用 corelocation 框架可以帮助理解为什么我的代码没有按照我想要的方式工作。我希望它跟踪行进的距离，但是当 View 启动时，它每次都会做不同的事情。有时它会跳到 1000 或另一个大值，或者它会随机增加。谁能看出为什么这段代码对我不起作用？

    - (void)viewDidLoad
{
    locationManager = [[CLLocationManager alloc] init];
    locationManager.desiredAccuracy = kCLLocationAccuracyBest;
    locationManager.delegate = self;
    locationManager.distanceFilter = 100; //update every 100 meters
    [locationManager startUpdatingLocation];
    startLocation = nil;

    [super viewDidLoad];
    // Do any additional setup after loading the view.
}
-(void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation {
    if (startLocation == nil)
    {
        totalDistanceBetween = 0;
        self.startLocation = newLocation;
    }
    CLLocationDistance distanceBetween = [newLocation distanceFromLocation:startLocation ];
    startLocation = newLocation;
    totalDistanceBetween += distanceBetween;
    totalDistanceBetween = totalDistanceBetween * 0.001; //convert to m value to km
    NSString *tripString = [[NSString alloc]
                            initWithFormat:@"%.02f",
                            totalDistanceBetween];
    distance.text = tripString;
}

Answer 1

让我突然想到的第一件事是您将 startLocation 设置为 nil after 您告诉位置管理器开始为您提供更新.

根据 startLocation 的定义/初始化/重用方式，它可能不包含您期望的初始值。