迅捷:"mapView.showUserLocation = true"返回“致命错误:在展开可选值(lldb)时意外发现nil" [英] Swift: "mapView.showUserLocation = true" returns "fatal error: unexpectedly found nil while unwrapping an Optional value (lldb) "

问题描述

因此，我试图使用"bar"或"pizza"之类的关键字在Swift中搜索本地商家.我将搜索链接到按钮操作，以便这些位置将在定义区域内的地图上弹出.但是，由于出现nil错误，我什至无法加载用户位置的应用程序.

So I'm trying to search for local businesses in Swift using keywords like "bar", or "pizza". I linked the search to a button action so that the locations will pop up on the map within a defined region. However, I can't even get the application to load with user location because I get a nil error.

这是我的AppDelegate:

Here's my AppDelegate:

import UIKit
import CoreLocation

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

var window: UIWindow?
var locationManager: CLLocationManager?

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
    // Override point for customization after application launch.
    locationManager = CLLocationManager()
    locationManager?.requestWhenInUseAuthorization()
    return true
}

func applicationWillResignActive(application: UIApplication) {
    // Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
    // Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
}

func applicationDidEnterBackground(application: UIApplication) {
    // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
    // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
}

func applicationWillEnterForeground(application: UIApplication) {
    // Called as part of the transition from the background to the inactive state; here you can undo many of the changes made on entering the background.
}

func applicationDidBecomeActive(application: UIApplication) {
    // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
}

func applicationWillTerminate(application: UIApplication) {
    // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
}


}

这是我的ViewController.swift:

And here's my ViewController.swift:

import Foundation
import UIKit
import MapKit

class ViewController: UIViewController, MKMapViewDelegate {

@IBOutlet weak var mapView: MKMapView!

@IBAction func searchBars(sender: AnyObject) {
    let request = MKLocalSearchRequest()
    request.naturalLanguageQuery = "Bar"
    request.region = mapView.region

    let search = MKLocalSearch(request: request)
    search.startWithCompletionHandler({(response: MKLocalSearchResponse!, error: NSError!) in

        if error != nil {
            println("Error occurred in search: \(error.localizedDescription)")
        } else if response.mapItems.count == 0 {
            println("No matches found")

            for item in response.mapItems as [MKMapItem] {
                println("Name = \(item.name)")
                println("Phone = \(item.phoneNumber)")
            }
        }
        })

}

func mapView(mapView: MKMapView!, didUpdateUserLocation userLocation: MKUserLocation!) {
    mapView.centerCoordinate = userLocation.location.coordinate
}

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    mapView.showsUserLocation = true
    mapView.delegate = self
}

@IBAction func zoomIn(sender: AnyObject) {
    let userLocation = mapView.userLocation

    let region = MKCoordinateRegionMakeWithDistance(userLocation.location.coordinate, 2000, 2000)
}

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


}

返回nil错误的行在我的ViewController.swift文件中的@IBAction func zoomIn下，并包含以下行:let region = MKCoordinateRegionMakeWithDistance(userLocation.location.coordinate，2000，2000).由于某种原因，它给出了nil值.

The line that returns the nil error is in my ViewController.swift file under @IBAction func zoomIn with the line: let region = MKCoordinateRegionMakeWithDistance(userLocation.location.coordinate, 2000, 2000). Which gives a nil value for some reason.

推荐答案

此行的工作是创建一个尚未实例化的mapView对象.

What you're doing with this line is creating a mapView object which is not instantiated yet.

weak var mapView: MKMapView!

出现错误是因为您试图将showsUserLocation属性更改为尚不存在的对象，它为空.

You get the error because you are trying to change showsUserLocation property to an object which doesn't exist yet, it's nil.

如果在情节提要中创建了地图，您需要做的是删除弱var线并放一个IBOutlet(Ctrl +单击并从情节提要中拖动).

What you need to do, if you created the map in a storyboard, is to remove the weak var line and put a IBOutlet instead (Ctrl + Click and drag from the storyboard).

这篇关于迅捷:"mapView.showUserLocation = true"返回“致命错误:在展开可选值(lldb)时意外发现nil"的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！