iOS定位问题：didUpdateLocations与授权回调未触发

问题说明 #

尝试获取设备定位时，locationManager(_:didChangeAuthorization:) 和 locationManager(_:didUpdateLocations:) 两个回调始终无法触发。系统会正常请求定位权限，且已完成授权，但第二次调用startLocation方法时，仅能看到权限授予的打印日志，回调仍无响应。

调用代码如下：

DispatchQueue.global(qos: .background).async {
    let gpsController = GPSController()
    gpsController.startLocation()
    
    sleep(10)
        DispatchQueue.main.async {
            gpsController.startLocation()
        }
}

我的GPSController实现代码：

import Foundation
import CoreLocation

class GPSController : NSObject, CLLocationManagerDelegate{

let locationManager: CLLocationManager = CLLocationManager()
static var lastLocation : CLLocation? = nil


func startLocation(){
    locationManager.delegate = self
    
    // 检查定位服务状态
    if CLLocationManager.locationServicesEnabled() {
        switch locationManager.authorizationStatus {
        case .notDetermined:
            print("notDetermined")
            locationManager.requestWhenInUseAuthorization()
            break
        case .restricted, .denied:
            print("Denied")
            break
        case .authorizedWhenInUse, .authorizedAlways:
            locationManager.startUpdatingLocation()
            print("authorizedWhenInUse")
        case .authorized:
            print("authorized")
            break
        @unknown default:
            print("@unknown")
            break
        }
    } else {
        print("turn off")
    }
    
}

func locationManager(_ manager: CLLocationManager, didChangeAuthorization status: CLAuthorizationStatus) {
    print("didChangeAuthorization")
    if manager.authorizationStatus == .authorizedWhenInUse {
        locationManager.startUpdatingLocation()
    }
}

func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
    print("didChangeAuthorization") // 此处打印内容错误，应为didUpdateLocations
    for currentLocation in locations{
        Loge("Location : \(currentLocation)")
        GPSController.lastLocation = currentLocation
    }
}


func locationManager(_ manager: CLLocationManager, didFailWithError error: Error) {
    print("error")
}    

解决方案 #

1. 核心问题：GPSController实例被提前回收 #

在后台队列闭包中创建的gpsController是局部变量，当闭包执行周期结束后，该实例会被ARC自动回收，导致CLLocationManager的代理失效，无法触发回调。

修复方式：

• 方式一：通过全局变量或类属性持有实例，保证其生命周期

// 在闭包外部声明持有变量
var gpsController: GPSController?

DispatchQueue.global(qos: .background).async {
    gpsController = GPSController()
    gpsController?.startLocation()
    
    sleep(10)
        DispatchQueue.main.async {
            gpsController?.startLocation()
        }
}

• 方式二：将GPSController设计为单例，确保全局唯一且不会被回收

class GPSController : NSObject, CLLocationManagerDelegate{
    static let shared = GPSController() // 单例实例
    let locationManager: CLLocationManager = CLLocationManager()
    static var lastLocation : CLLocation? = nil

    private override init() { // 私有化构造方法，避免创建多个实例
        super.init()
        locationManager.delegate = self // 初始化时统一设置代理，无需重复调用
    }

    // 剩余方法保持不变
}

// 调用方式
DispatchQueue.global(qos: .background).async {
    GPSController.shared.startLocation()
    
    sleep(10)
        DispatchQueue.main.async {
            GPSController.shared.startLocation()
        }
}

2. 次要问题修正 #

• 修正didUpdateLocations中的打印错误，将print("didChangeAuthorization")改为print("didUpdateLocations")，便于确认回调是否触发。
• 确保Info.plist中添加了对应权限描述：
  • 使用requestWhenInUseAuthorization时，需添加NSLocationWhenInUseUsageDescription键并补充描述文本；
  • 使用requestAlwaysAuthorization时（iOS 11+），需添加NSLocationAlwaysAndWhenInUseUsageDescription键。

内容的提问来源于stack exchange，提问作者RCH