MKAnnotations 未显示在地图上 iOS 9 / Swift 2.0

Posted 2023-03-16

【中文标题】MKAnnotations 未显示在地图上 iOS 9 / Swift 2.0

【英文标题】：MKAnnotations Not Showing Up On Map iOS 9 / Swift 2.0

【发布时间】：2015-11-05 07:22:32

【问题描述】：

尝试使用显示其名称和地址的注释在地图上显示 100 个 EV 充电站，但以下代码应显示的 100 个注释中只有一个显示在地图上。

代码构建良好并且没有任何错误标志，但我感觉地图注释代码有问题。在运行时在调试器中收到一条很长的错误消息：

2015-11-05 01:07:47.758 JSON[65210:8214517] 此应用程序正在从后台线程修改自动布局引擎，这可能导致引擎损坏和奇怪的崩溃。这将在未来的版本中导致异常。 堆：（ 0 核心基础 0x000000010dd67f45 __exceptionPreprocess + 165 1 libobjc.A.dylib 0x000000010fdc2deb objc_exception_throw + 48 2 核心基础 0x000000010dd67e7d +[NSException raise:format:] + 205 3 基础 0x000000010e35c289 _AssertAutolayoutOnMainThreadOnly + 79 4 基础 0x000000010e1bccce -[NSISEngine withBehaviors:performModifications:] + 31 5 UIKit 0x000000010e95ed4a-[UIView（层次结构）_postMovedFromSuperview：] + 575 6 UIKit 0x000000010e96c7e7-[UIView（内部）_addSubview:positioned:relativeTo:] + 1967 7 MapKit 0x000000010e6f2c90-[MKAnnotationContainerView addSubview:] + 128 8 MapKit 0x000000010e6f283e-[MKAnnotationContainerView addAnnotationView:allowAnimation:] + 466 9 MapKit 0x000000010e5ff976-[MKMapView addAnnotationRepresentation:allowAnimation:] + 487 10 MapKit 0x000000010e66ed64-[MKAnnotationManager _addRepresentationForAnnotation:] + 721 11 MapKit 0x000000010e66e3be -[MKAnnotationManager updateVisibleAnnotations] + 1551 12 MapKit 0x000000010e66f314-[MKAnnotationManager observeValueForKeyPath:ofObject:change:context:] + 859 13 基础 0x000000010e17b610 NSKeyValueNotifyObserver + 347 14 基础

//
//  ViewController.swift
//  JSON
//
//  Created by Matt Velker on 11/4/15.
//  Copyright © 2015 slingshot. All rights reserved.
//

import UIKit
import CoreLocation
import MapKit

class ViewController: UIViewController 

@IBOutlet weak var map: MKMapView!
var annotations = [MKPointAnnotation](count: 100, repeatedValue: MKPointAnnotation())

override func viewDidLoad() 
    super.viewDidLoad()

    var mapLat:CLLocationDegrees = CLLocationDegrees(40.596061)
    var mapLong:CLLocationDegrees = CLLocationDegrees(-98.819799)
    var mapLongDelta:CLLocationDegrees = CLLocationDegrees(50)
    var mapLatDelta:CLLocationDegrees = CLLocationDegrees(50)
    var mapCenterLocation:CLLocationCoordinate2D = CLLocationCoordinate2DMake(mapLat, mapLong)
    var mapSpan:MKCoordinateSpan = MKCoordinateSpanMake(mapLatDelta, mapLongDelta)
    var mapRegion:MKCoordinateRegion = MKCoordinateRegionMake(mapCenterLocation, mapSpan)
    map.setRegion(mapRegion, animated: true)

    let url = NSURL(string: "https://developer.nrel.gov/api/alt-fuel-stations/v1.json?fuel_type=ELEC&state=CA&limit=100&api_key=vo1v1jn4eZC83ni2pII19vYmzLmk7UQzID4VZsZT&format=JSON")!
    let task = NSURLSession.sharedSession().dataTaskWithURL(url)  (data, response, error) -> Void in
        if let urlContent = data 
            do 
                let jsonResult = try NSJSONSerialization.JSONObjectWithData(urlContent, options: NSJSONReadingOptions.MutableContainers)
                //print(jsonResult)
                var lat: [CLLocationDegrees] = []
                var long: [CLLocationDegrees] = []
                var location: CLLocationCoordinate2D
                var locations: [CLLocationCoordinate2D] = []
                if let jsonArrayOfDictionaries = jsonResult["fuel_stations"] 
                    for var x=0; x < jsonArrayOfDictionaries!.count; x++ 
                        lat.append(jsonArrayOfDictionaries![x]["latitude"] as! CLLocationDegrees)
                        long.append(jsonArrayOfDictionaries![x]["longitude"] as! CLLocationDegrees)
                        location = CLLocationCoordinate2DMake(lat[x], long[x])
                        locations.append(location)
                        self.annotations[x].coordinate = locations[x]
                        self.annotations[x].title = jsonArrayOfDictionaries![x]["station_name"] as? String
                        self.annotations[x].subtitle = jsonArrayOfDictionaries![x]["street_address"] as? String
                    
                
             catch 
                print("JSON serialization failed")
            

        
    
    task.resume()
    map.addAnnotations(annotations)


override func didReceiveMemoryWarning() 
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.

【参考方案1】：

此应用程序正在从后台线程修改自动布局引擎，...

...
self.annotations[x].coordinate = locations[x] //this line causes the error log
...

您应该在后台加载数据，然后在完成后更新主线程中的视图。