ios - CLLocationDistance 不起作用 - 快速

Question

我在使用这段代码时遇到问题，我无法计算两个位置之间的距离。我已经在互联网上搜索过，但无法解决。这是我的 didUpdateLocations 函数:

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

    var userLocation:CLLocation = locations[0] as CLLocation
    var startLocation = userLocation
    var endLocation = userLocation
    if x == 0 {
        var startLocation = userLocation
        star.text = "\(startLocation)"
    }
    if x > 0 {
        var endLocation = userLocation
        end.text = "\(endLocation)"
        let distance: CLLocationDistance = startLocation.distanceFromLocation(endLocation)
        println(distance)
    }
    x = x + 1
}

Answer 1

您只需将 var startLocation 声明为可选但不在您的函数内。

var startLocation :CLLocation! 

然后在 didUpdate 函数中测试 startLocation 变量是否为 nil:

func locationManager(manager: CLLocationManager!, didUpdateLocations locations: [AnyObject]!) {
    if startLocation == nil {
        startLocation = locations.first as? CLLocation
    }
    let distance = startLocation.distanceFromLocation(locations.last as! CLLocation)
    println( "\(startLocation)")
    println( "\(locations.last as! CLLocation)")
    println("DISTANCE: \(distance)")
}