不知道如何在 SwiftUI (Xcode 12.4) 中打开地图

Posted 2023-02-24

【中文标题】不知道如何在 SwiftUI (Xcode 12.4) 中打开地图

【英文标题】：Don't know how to open the Map in SwiftUI (Xcode 12.4)

【发布时间】：2021-01-31 21:38:04

【问题描述】：

我刚开始在 Xcode 中编程，有些东西对我来说似乎还是有点难以理解。我在 medium.com 上找到了一个带有代码的教程，以使用 MapKit 实现当前用户位置。获取用户位置并将其显示在地图上的代码写在 MapViewController.swift 文件和类中，如下所示。

import Foundation
import UIKit
import MapKit
import CoreLocation

class MapViewController: UIViewController, CLLocationManagerDelegate 
    
    let mapView = MKMapView()
    let locationManager = CLLocationManager()
    
    override func viewDidLoad() 
        super.viewDidLoad()
        setupMapView()
        checkLocationServices()
        // Do any additional setup after loading the view.
    
    
    func setupMapView() 
        view.addSubview(mapView)
        mapView.translatesAutoresizingMaskIntoConstraints = false
        mapView.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
        mapView.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
        mapView.rightAnchor.constraint(equalTo: view.safeAreaLayoutGuide.rightAnchor).isActive = true
        mapView.leftAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leftAnchor).isActive = true 
    
    
    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) 
        guard let location = locations.last else  return 
        let region = MKCoordinateRegion.init(center: location.coordinate, latitudinalMeters: 4000, longitudinalMeters: 4000)
        mapView.setRegion(region, animated: true)
    
    
    func checkLocalAuthorization() 
        switch CLLocationManager.authorizationStatus() 
        case .authorizedWhenInUse:
            mapView.showsUserLocation = true
            followUserLocation()
            locationManager.startUpdatingLocation()
            break
        case .denied:
            // Show alert
            break
        case .notDetermined:
            locationManager.requestWhenInUseAuthorization()
        case .restricted:
            // Show alert
            break
        case .authorizedAlways:
            break
        @unknown default:
        fatalError()
        
    
    
    func checkLocationServices() 
        if CLLocationManager.locationServicesEnabled() 
            setupLocationManager()
            checkLocalAuthorization()
         else 
            // user did not turn it on
        
    
    
    func followUserLocation() 
        if let location = locationManager.location?.coordinate 
            let region = MKCoordinateRegion.init(center: location, latitudinalMeters: 4000, longitudinalMeters: 4000)
            mapView.setRegion(region, animated: true)
        
    
    
    func locationManager(_ manager: CLLocationManager, didChangeAuthorization status: CLAuthorizationStatus) 
        checkLocalAuthorization()
    
    
    func setupLocationManager() 
        locationManager.delegate = self
        locationManager.desiredAccuracy = kCLLocationAccuracyBest
    

问题是我不知道如何运行代码以使地图可见。当我在 ContentView.swift 中调用 MapViewController() 类时，如下所示，我收到错误“属性'body'的返回类型要求'MapViewController'符合'View'”和“静态方法'buildBlock'需要'MapViewController'符合‘观点’”。有人可以解释我如何修复错误并只查看地图吗？非常感谢提前？？？ ？？？ ????

import SwiftUI
import UIKit
import CoreLocation
import MapKit

struct ContentView: View 
var body: some View 
    MapViewController()
    


struct ContentView_Previews: PreviewProvider 
    static var previews: some View 
        ContentView()
    

【问题讨论】：

您需要使用 UIViewControllerRepresentable 来包含您的 MapViewController。

别人已经给出了解决方案。但它不起作用的原因是因为 UIViewController 是一个 UIKit 组件，并且您使用的是 SwiftUI，这需要 var body 中的任何内容最终 return 符合 View 的内容并将其包装成UIViewControllerRepresentable 使其符合。

谢谢大家的解释！ ??????????????????

【参考方案1】：

你需要一个 UIViewControllerRepresentable：

struct MapViewRepresentable: UIViewControllerRepresentable 
    func makeUIViewController(context: Context) -> some UIViewController 
        return MapViewController()
    
    
    func updateUIViewController(_ uiViewController: UIViewControllerType, context: Context) 
    



struct ContentView: View 
    var body: some View 
        MapViewRepresentable() //<< here use your UIViewControllerRepresentable
    

【讨论】：

谢谢大家回答我的问题，解释和代码！我现在理解问题并且代码有效！ ??????