Swift：“mapView.showUserLocation = true”返回“致命错误：意外地发现零，而解包可选值（lldb）”

所以我试图用“bar”或“pizza”这样的关键词来searchSwift中的本地商家。 我将search链接到一个button动作，以便位置将在定义的区域内的地图上popup。 但是，我甚至不能让应用程序加载用户位置，因为我得到一个零错误。

这是我的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:. } } 

这里是我的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，在@IBAction func zoomIn中用下面这行代码：let region = MKCoordinateRegionMakeWithDistance（userLocation.location.coordinate，2000，2000）。 由于某种原因，这给出了一个零值。

Answer 1

你用这一行做的是创build一个尚未实例化的mapView对象。

 weak var mapView: MKMapView! 

你会得到这个错误，因为你试图将showsUserLocation属性改为一个不存在的对象，它是零。

如果您在故事板中创build了地图，则需要执行的操作是删除弱变线，然后放置IBOutlet （Ctrl +单击并从故事板拖动）。

Answer 2

非常感谢Skoua的帮助。 在我帮助IBOutlet之后，我发现自己出了什么问题。

这是更正的代码。

 @IBAction func searchBars(sender: AnyObject) { matchingItems.removeAll() 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") //This is where the problem occured } else { println("Matches found") //I needed to insert an else statement for matches being found for item in response.mapItems as [MKMapItem] { //This prints the 'matches' into [MKMapItem] println("Name = \(item.name)") println("Phone = \(item.phoneNumber)") self.matchingItems.append(item as MKMapItem) println("Matching items = \(self.matchingItems.count)") var annotation = MKPointAnnotation() annotation.coordinate = item.placemark.coordinate annotation.title = item.name self.mapView.addAnnotation(annotation) } } }) }