我想使用JSON与Google Maps SDK一起放置多个标记

Question

I'm trying to add multiple markers by using google maps SDK.i get data but multiple markers are not inserted please any help welcome

I try following code:

import UIKit
import GoogleMaps
import GooglePlaces

class ViewController: UIViewController,GMSMapViewDelegate {


override func viewDidAppear(_ animated: Bool) {
    let getPlaces: String = "https://maps.googleapis.com/maps/api/place/nearbysearch/json?location=-33.8670522,151.1957362&radius=500&type=restaurant&key=AIzaSyCNKHyGGXXfsRq6bsiG6EmtQiy7ApN2TFg"
    let frame = GMSCameraPosition.camera(withLatitude: 33.8670522, longitude: 151.1957362, zoom: 12.0)
    let mapview = GMSMapView.map(withFrame: self.view.bounds, camera: frame)


    let session = URLSession.shared.dataTask(with: URL(string: getPlaces)!) { (data, response, error) in
        do{
            let jsonResult = try JSONSerialization.jsonObject(with: data!, options: JSONSerialization.ReadingOptions.mutableContainers) as! NSDictionary
            // print(jsonResult)


            let returnedPlaces: NSArray? = jsonResult["results"] as? NSArray

            if returnedPlaces != nil {

                for index in 0..<returnedPlaces!.count {

                    if let returnedPlace = returnedPlaces?[index] as? NSDictionary {

                        var placeName = ""
                        var latitude = 0.0
                        var longitude = 0.0


                        if let name = returnedPlace["name"] as? NSString {
                            placeName = name as String
                        }

                        if let geometry = returnedPlace["geometry"] as? NSDictionary{
                            if let location = geometry["location"] as? NSDictionary {
                                if let lat = location["lat"] as? Double {
                                    latitude = lat
                                }
                                if let lng = location["lng"] as? Double {
                                    longitude = lng
                                }
                            }
                        }
                        DispatchQueue.main.async{
                            // let marker = index

                            let marker = GMSMarker()
                            marker.position = CLLocationCoordinate2DMake(latitude, longitude)
                            marker.title = placeName

                           // self.view = mapview
                            marker.map = mapview
                            print("HI see this \(placeName)")
                        }

                    }


                }
                self.view = mapview
             }

        }catch
        {
            print("Error")
        }
    }
    session.resume()
}

I get exception like :

2017-04-27 12:08:26.207 Inte-GoogleMaps[759:15071] This application is modifying the autolayout engine from a background thread after the engine was accessed from the main thread. This can lead to engine corruption and weird crashes.

Terminating app due to uncaught exception 'GMSThreadException', reason: 'The API method must be called from the main thread'

Answer 1

The assignment self.view = map view is outside your main queue dispatch queue block (and hence being run on a background thread). This code changes the state of a view and therefore must run on the main thread or it will cause problems for the UI engine (all iOS UI code must run on the main thread).

This is why you are seeing the warning about running Autolayout on a background thread.

You have the same line commented out in the DispatchQueue.main block above. This is the correct place for it, so you were obviously already thinking along the right lines!

You should delete the line from its current position, and uncomment the commented line. I've run your code on my machine with this change, and it works ok - it adds a bunch of markers around the area of Pyrmont in Sydney.

You also need to change the code that centers the map - you are missing a minus sign in front of the latitude - as posted it zooms to somewhere off the coast of Japan. You probably also want to zoom in a bit - zoom level 15 looks good on my simulator.

The camera position code should be:

let frame = GMSCameraPosition.camera(withLatitude: -33.8670522, longitude: 151.1957362, zoom: 15.0)