iOS 定位说明

一、精度模式

extern const CLLocationAccuracy kCLLocationAccuracyBestForNavigation 

    //最适合导航用的定位  iOS4.0以后新增（我们现在用的是这个）

extern const CLLocationAccuracy kCLLocationAccuracyBest;

    //精度最高的定位

extern const CLLocationAccuracy kCLLocationAccuracyNearestTenMeters;

    //定位精度在10米以内

extern const CLLocationAccuracy kCLLocationAccuracyHundredMeters;

    //定位精度在100米以内

extern const CLLocationAccuracy kCLLocationAccuracyKilometer;

     //定位精度在1000米以内

extern const CLLocationAccuracy kCLLocationAccuracyThreeKilometers;

     //定位精度在3000米以内

二、左上角蓝条

必要条件：
1.app 开启 allowsBackgroundLocationUpdates 后台刷新

2.app 请求后台刷新（使用允许定位）、但是用户只给了使用期间允许定位，就会出现蓝条，当重新给定始终允许刷新时，蓝条消失。

app监测到用户给的权限低于申请的权限就会在app进入后台时，
停止刷新定位、此时就会出现（高德地图）左上角蓝条持续一会儿，就消失的情况。

代码如下：

//
//  LocationManager.swift
//  LocationUpdates
//
//  Created by Quinn Von on 2020/3/20.
//  Copyright © 2020 Quinn Von. All rights reserved.
//

import Foundation
import CoreLocation
import UIKit

class LocationManager:NSObject {

    //MARK: - Properties
    static let shared   = LocationManager()
    private var locationManager = CLLocationManager()
    private var observersList = [String:LocationUpdateHandler]()
    typealias LocationUpdateHandler = ((_ manager: CLLocationManager,  _ locations: [CLLocation])->Void)
    
    //MARK:- Initializer
    override init() {
        super.init()
        setupLocationManager()
        getLocationAuthentication()
        print("Location Manager Initalized")
    }
    
    func stopLocationManager(){
        locationManager.stopUpdatingLocation()
    }
    //MARK: - Functions
    
    func addLocationUpdateObserver(_ observer: NSObject, completionHandler: @escaping LocationUpdateHandler) {
        observersList[observer.description] = completionHandler
    }

    func removeLocationUpdateObserver(_ observer: NSObject){
        observersList.removeValue(forKey: observer.description)
    }
    
    private func setupLocationManager(){
        if CLLocationManager.locationServicesEnabled() {
            locationManager.delegate = self
            locationManager.desiredAccuracy = kCLLocationAccuracyBestForNavigation
            locationManager.startUpdatingLocation()
            locationManager.distanceFilter = 1.0
        }
        if #available(iOS 9.0, *) {
            // 如果APP处于后台,则会出现蓝条
            locationManager.allowsBackgroundLocationUpdates = true
        }
    }
    
    func getLocationAuthentication(){
        switch CLLocationManager.authorizationStatus() {
        case .authorizedWhenInUse:
            break
        case .denied:
            locationManager.requestWhenInUseAuthorization()
            break
        case .authorizedAlways:
            break
        case .restricted:
            locationManager.requestWhenInUseAuthorization()
            break
        case .notDetermined:
            locationManager.requestWhenInUseAuthorization()
            break
        default:
            break
        }
    }
}

extension LocationManager:CLLocationManagerDelegate{
    //MARK: - CLLocationManagerDelegates
    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        //MARK: - Locations are being fetched here and posted to observer
        observersList.forEach({$0.value(manager, locations)})
    }
    
    func locationManager(_ manager: CLLocationManager, didFailWithError error: Error) {
    }
    
    func locationManager(_ manager: CLLocationManager, didChangeAuthorization status: CLAuthorizationStatus) {
    }
}

class SceneDelegate:

    func sceneDidEnterBackground(_ scene: UIScene) {
        // Called as the scene transitions from the foreground to the background.
        // Use this method to save data, release shared resources, and store enough scene-specific state information
        // to restore the scene back to its current state.
        LocationManager.shared.stopLocationManager()
    }

三、实心定位

APP 定位时，为实心的

四、空心定位

APP 定位时，但未成功，例如，app打开后迅速放到后台，有可能会出现、多试几次