Question

func locationManager(manager: CLLocationManager, didUpdateLocations locations: [AnyObject]){
    if startLocation == nil {
        startLocation = locations.first as! CLLocation
    }
    else{
        let distance = startLocation.distanceFromLocation(locations.last as! CLLocation)
        let lastDistance = lastLocation.distanceFromLocation(locations.last as! CLLocation)
        traveledDistance += lastDistance
        //print("\(startLocation)")
        //print("\(lastLocation)")
        //print("\(traveledDistance)")
        print("\(distance)")
        distanceLabel.text = "\(distance)"
    }
    lastLocation = locations.last as! CLLocation
}

我在stackoverflow上找到了上面的代码，如果我开车或朝一个方向行走，但是当我转身回到起点时，distane是0m。如果有人可以详细解释代码，那将会很好或者给我一些建议。感谢

Answer 1

这不是微不足道的吗？您正在打印从distance反复计算的startLocation，它将永远不会在您的代码中发生变化。如果我从点A开始并转到B（以米为单位会有一些距离），然后返回A并从startLocation计算（这总是A）它应该为零。：D

我没有尝试你的代码，但在我看来这就是那里发生的事情。相反，请打印traveledDistance，这是随着您移动时总是会增加的值。

修复你的代码：

print("\(traveledDistance)")
distanceLabel.text = "\(traveledDistance)"

如果您只需要总距离，我会将代码更改为：

func locationManager(manager: CLLocationManager, didUpdateLocations locations: [AnyObject]) {

    /* for the ever first call the if check should fail because lastLocation is initially nil in your code (I assume) */
    if lastLocation != nil {

        /* this will start adding a distance at the second call of the callback */
        traveledDistance += lastLocation.distanceFromLocation(locations.last as! CLLocation)

        print("\(traveledDistance)")
        distanceLabel.text = "\(traveledDistance)"
    }

    /* here we are saving the current location to our variable for later calculation */
    lastLocation = locations.last as! CLLocation
}

斯威夫特获得的总距离为9

1 个答案: