iOS Swift 坐标函数返回 nil

Question

我正在研究将城市(字符串)转换为坐标的函数。但是，当我调用该函数时，结果是“(0.0, 0.0)”。应该是经纬度。

请帮帮我。谢谢!

这是函数

func getCoordinates(huidigeLocatie: String) -> (lat: CLLocationDegrees, long: CLLocationDegrees) {

    var lat:CLLocationDegrees
    var long:CLLocationDegrees

    var geocoderHuidigeLocatie = CLGeocoder()

    geocoderHuidigeLocatie.geocodeAddressString(huidigeLocatie, completionHandler:
        {(placemarks: [AnyObject]!, error: NSError!) in

            if error != nil {

                println("Geocode failed with error: \(error.localizedDescription)")

            } else if placemarks.count > 0 {

                let placemark = placemarks[0] as CLPlacemark
                let location = placemark.location

                var lat = location.coordinate.latitude
                var long = location.coordinate.longitude

            }
    })

    return (lat: CLLocationDegrees(), long: CLLocationDegrees())
}

Answer 1

这里有两个问题:

1. 您想返回实际的 lat 和 long 变量，而不是 CLLocationDegrees()。

2. 一个更微妙的问题是您正在调用一个异步返回其结果的函数，因此您无法立即返回值。相反，您可以使用自己的 completionHandler 模式。

例如:

func getCoordinates(huidigeLocatie: String, completionHandler: (lat: CLLocationDegrees!, long: CLLocationDegrees!, error: NSError?) -> ()) -> Void {

    var lat:CLLocationDegrees
    var long:CLLocationDegrees

    var geocoderHuidigeLocatie = CLGeocoder()

    geocoderHuidigeLocatie.geocodeAddressString(huidigeLocatie) { (placemarks: [AnyObject]!, error: NSError!) in

        if error != nil {

            println("Geocode failed with error: \(error.localizedDescription)")

            completionHandler(lat: nil, long: nil, error: error)

        } else if placemarks.count > 0 {

            let placemark = placemarks[0] as CLPlacemark
            let location = placemark.location

            let lat = location.coordinate.latitude
            let long = location.coordinate.longitude

            completionHandler(lat: lat, long: long, error: nil)
        }
    }
}

你可以这样调用它:

getCoordinates(string) { lat, long, error in
    if error != nil { 
        // handle the error here 
    } else {
        // use lat, long here
    }
}

// but not here