数据未通过 Segue

Question

我有一个稍微令人困惑的问题，我正在尝试将位置数据从 tableview 发送到 mapkit。我的 tableview 加载各种信息以列出位置的名称，当我单击一个单元格时，它会进入带有数据的导航视图，但是它似乎没有发送数据和发现错误的 nil 问题。我确实有这个相同的 tableview 连接到不同的控制器，它没有问题。

这是我的主视图控制器上的 prepareForSegue

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "mapLocation" {
        if let detailsVC = segue.destination as? mapLocation {
            if let tr = sender as? newTracks {
                detailsVC.track = tr
            }
        }
    }
}

这是要转到的 mapkit 视图

import UIKit
import MapKit
import CoreLocation

class mapLocation: UIViewController, MKMapViewDelegate {


@IBOutlet weak var mapView: MKMapView!

var track: newTracks!

override func viewDidLoad() {
    super.viewDidLoad()

    let sourceloaction = CLLocationCoordinate2D(latitude: track.lat, longitude: track.lon)
    let destinationLocation = CLLocationCoordinate2D(latitude: track.lat, longitude: track.lon)

    let sourcePlacemark = MKPlacemark(coordinate: sourceloaction, addressDictionary: nil)
    let destinationPlacemark = MKPlacemark(coordinate: destinationLocation, addressDictionary: nil)

    let sourceMapItem = MKMapItem(placemark: sourcePlacemark)
    let destinationMapItem = MKMapItem(placemark: destinationPlacemark)

    let sourceAnnotation = MKPointAnnotation()
    sourceAnnotation.title = track.name

    if let location = sourcePlacemark.location {
        sourceAnnotation.coordinate = location.coordinate
    }

    let destinationAnnotation = MKPointAnnotation()
    destinationAnnotation.title = track.name

    if let location = destinationPlacemark.location {
        destinationAnnotation.coordinate = location.coordinate
    }

    self.mapView.showAnnotations([sourceAnnotation,destinationAnnotation], animated: true)

    let directionRequest = MKDirectionsRequest()
    directionRequest.source = sourceMapItem
    directionRequest.destination = destinationMapItem
    directionRequest.transportType = .automobile

    let directions = MKDirections(request: directionRequest)

    directions.calculate {
        (response, error) -> Void in

        guard let response = response else {
            if let error = error {
                print("Error: \(error)")
            }
            return
        }

        let route = response.routes[0]
        self.mapView.add((route.polyline), level: MKOverlayLevel.aboveRoads)

        let rect = route.polyline.boundingMapRect
        self.mapView.setRegion(MKCoordinateRegionForMapRect(rect), animated: true)
    }


}


func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) ->     MKOverlayRenderer {
    let renderer = MKPolylineRenderer(overlay: overlay)
    renderer.strokeColor = UIColor.red
    renderer.lineWidth = 4.0

    return renderer
}



}

这是我的 NewTracks 结构，数据被加载到/从：

import Foundation
import FirebaseDatabase

struct newTracks {


let name: String!
let trackId: Int!
let postcode: String!
let trackType: String!
let locID: Int!
let lat: Double!
let lon: Double!
let phoneNumber: String!
let email: String!
let rating: Double!
let numrating: Double!
let totalrating: Double!
let ref: FIRDatabaseReference?



init(name: String, trackId: Int, postcode: String, trackType: String, trackURL: String, locID: Int, lat: Double, lon: Double, phoneNumber: String, email: String, rating: Double, numrating: Double, totalrating: Double) {
    self.name = name
    self.trackId = trackId
    self.ref = nil
    self.postcode = postcode
    self.trackType = trackType
    self.locID = locID
    self.lat = lat
    self.lon = lon
    self.phoneNumber = phoneNumber
    self.email = email
    self.rating = rating
    self.numrating = numrating
    self.totalrating = totalrating

}

init(snapshot: FIRDataSnapshot) {
    let snapshotValue = snapshot.value as! [String: AnyObject]
    name = snapshotValue["name"] as! String
    trackId = snapshotValue["id"]as! Int
    postcode = snapshotValue["postcode"]as! String
    trackType = snapshotValue["type"]as! String
    locID = snapshotValue["locID"]as! Int
    lat = snapshotValue["lat"]as! Double
    lon = snapshotValue["long"]as! Double
    phoneNumber = snapshotValue["phone"]as! String
    email = snapshotValue["email"]as! String
    rating = snapshotValue["rating"]as! Double
    ref = snapshot.ref
    numrating = snapshotValue["numrating"] as! Double
    totalrating = snapshotValue["totalrating"] as! Double

}

func toAnyObject() -> Any {
    return [
        "name": name,
        "trackId": trackId,
        "postcode": postcode,
        "trackType": trackType,
        "locID": locID,
        "lat": lat,
        "lon": lon,
        "phoneNumber": phoneNumber,
        "email": email,
        "rating": rating,
        "numrating": numrating,
        "totalrating": totalrating
            ]
}

}

错误发生在 mapLocation VC 中的行上

let sourceloaction = CLLocationCoordinate2D(latitude: track.lat, longitude: track.lon)

由于某种原因未传递 lat 和 lon 值。

在我之前的 VC 中，segue 可以很好地处理数据，我所要做的就是添加

var track: newTracks

这使得通信可以回到数据的来源，但由于某种原因，它现在似乎无法正常工作。我知道这将是我错过的基本简单的事情。

这是我的原始 segue 代码，适用于普通 View COntroller，而不是 UINavigationController

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "TrackDetailVC" {
        if let detailsVC = segue.destination as? TrackDetailVC {
            if let tr = sender as? newTracks {
                detailsVC.track = tr
            }
        }
    }
}

Answer 1

是的，当您的 viewController 嵌入到 UINavigationController 中时，您必须遍历链的各个部分，直到找到您想要的控制器。像这样的东西应该可以工作：

override function prepare(for segue: UIStoryBoardSegue, sender: Any?) {
   if segue.identifier == “TrackDetailVC” {
       if let nav = segue.destinationVC as? UINavigationController {
           if let detailsVC = nav.viewControllers[0] as? TrackDetailVC {
               if let tr = sender as? newTracks {
                   detailsVC.track = tr
               }
           }
       }
   }
}

Answer 2

发件人不能符合类型 newTracks。用断点做一些调试，也许看看为什么这个演员不起作用。尝试创建一个名为 newTracks 的变量并明确地给它一个类型，并将其设置为你想要的。然后制作detailsVc.track = newTracks