将城市名称转换为Swift中的坐标 [英] Converting a city name to coordinates in Swift

问题描述

我在SO上看到了几个问题，但所有这些问题都在Swift 2中老化。
我从Apple网站获得了将城市名称转换为经度和纬度的功能，但我不确定该函数将返回什么因为return语句后没有任何内容），我应该通过什么。

I saw few questions on SO but all of them are old in Swift 2. I got this function from Apple website to convert a city name to latitude and longitude but I am not sure what the function will return (since there is nothing after return statement) and what should I pass. Would someone explain it a lil or show me how to use it please.

func getCoordinate( addressString : String, 
        completionHandler: @escaping(CLLocationCoordinate2D, NSError?) -> Void ) {
    let geocoder = CLGeocoder()
    geocoder.geocodeAddressString(addressString) { (placemarks, error) in
        if error == nil {
            if let placemark = placemarks?[0] {
                let location = placemark.location!

                completionHandler(location.coordinate, nil)
                return
            }
        }

        completionHandler(kCLLocationCoordinate2DInvalid, error as NSError?)
    }
}

推荐答案

如下所示：

You can do it as follow:

import CoreLocation

func getCoordinateFrom(address: String, completion: @escaping(_ coordinate: CLLocationCoordinate2D?, _ error: Error?) -> () ) {
    CLGeocoder().geocodeAddressString(address) { placemarks, error in
        completion(placemarks?.first?.location?.coordinate, error)
    }
}

用法：

getCoordinateFrom(address: "Rio de Janeiro, Brazil") { coordinate, error in
    guard let coordinate = coordinate, error == nil else { return }
    // don't forget to update the UI from the main thread
    DispatchQueue.main.async {
        print(coordinate) // CLLocationCoordinate2D(latitude: -22.910863800000001, longitude: -43.204543600000001)
    }

}

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