Swift 使用 CoreLocation 获取设备的经纬度

请求权限

需要在 Targets 中的 Info 中添加：

Privacy - Location When In Use Usage Description

或者

Privacy - Location Always Usage Description

Privacy - Location Always and When In Use Usage Description

代码

import CoreLocation

class LocationDataManager: NSObject, CLLocationManagerDelegate, ObservableObject {
    
    private var locationManager = CLLocationManager()
    
    @Published var currentPosition: CLLocationCoordinate2D?
    @Published var currentSpeed: CLLocationSpeed?
    @Published var authorizationStatus: CLAuthorizationStatus?
    
    override init() {
        super.init()
        locationManager.delegate = self
        locationManager.desiredAccuracy = kCLLocationAccuracyBestForNavigation
//        locationManager.distanceFilter = 10     // 感觉没啥用
    }
    
    func locationManagerDidChangeAuthorization(_ manager: CLLocationManager) {
        
        switch manager.authorizationStatus {
        case .authorizedWhenInUse:
            authorizationStatus = .authorizedWhenInUse
            manager.startUpdatingLocation()
            break
            
        case .restricted:       // 受限
            authorizationStatus = .restricted
            manager.stopUpdatingLocation()
            break
            
        case .denied:           // 拒绝
            authorizationStatus = .denied
            manager.stopUpdatingLocation()
            break
            
        case .notDetermined:    // 等待回应
            authorizationStatus = .notDetermined
            manager.requestWhenInUseAuthorization()
            break
            
        default:
            break
        }
    }
    
    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        if let newPosition = manager.location {
            currentPosition = newPosition.coordinate
            currentSpeed = newPosition.speed
        }
    }
    
    func locationManager(_ manager: CLLocationManager, didFailWithError error: Error) {
        print("error: \(error.localizedDescription)")
    }
    
    func stopLocation() {
        locationManager.stopUpdatingLocation()
    }
    
}

具体使用：

import SwiftUI

struct ContentView: View {
    
    @StateObject var locationDataManager = LocationDataManager()
    
    var body: some View {
        VStack {
            
            switch locationDataManager.authorizationStatus {
            
            case .authorizedWhenInUse:
                Text("Your current location is:")
                Text(locationDataManager.currentPosition?.latitude.description ?? "Error")
                Text(locationDataManager.currentPosition?.longitude.description ?? "Error")
                
                   
            case .restricted, .denied:
                Text("前往 App 的设置中开启定位...")
                
            case .notDetermined:
                Text("等待授权...")
                ProgressView()
                
            default:
                ProgressView()
            }
        }
        .onReceive(locationDataManager.$currentPosition) { position in
            if locationDataManager.authorizationStatus == .authorizedWhenInUse {
                print("Location Is Change")
            }
        }
    }
}

#Preview {
    ContentView()
}

定位精度

有两个属性 .desiredAccuracy 与 .distanceFilter。

.desiredAccuracy

kCLLocationAccuracyBestForNavigation		// 精度最高，一般用于导航
kCLLocationAccuracyBest									// 精确度最佳
kCLLocationAccuracynearestTenMeters			// 精确度10m以内
kCLLocationAccuracyHundredMeters				// 精确度100m以内
kCLLocationAccuracyKilometer						// 精确度1000m以内
kCLLocationAccuracyThreeKilometers			// 精确度3000m以内

.distanceFilter

我们无法直接控制 loctionManager 更新的频率，但可使用 distanceFilter 属性（单位米）进行间接控制。

它指设备（水平或垂直）移动多少米后才将另一个更新发送给委托。定位要求的精度越高，distanceFilter 属性的值越小，应用程序的耗电量就越大。

但是目前看下来，好像没什么效果。

参考：

1. Updating the User’s Location with Core Location and Swift Concurrency in SwiftUI
2. Tutorial: Connecting Core Location to a SwiftUI App
3. SwiftUI获取用户的位置信息 CLLocationManager，CLLocationManagerDelegate
4. Swift - 使用CoreLocation实现定位（经纬度、海拔、速度、距离等）
5. An example how to use onReceive with @published
6. difference between desiredAccuracy and distanceFilter