【发布时间】：2015-04-26 19:06:02
【问题描述】：
所以我尝试使用“bar”或“pizza”等关键字在 Swift 中搜索本地企业。我将搜索链接到一个按钮操作，以便这些位置将在定义区域内的地图上弹出。但是，我什至无法让应用程序加载用户位置，因为我得到一个 nil 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 @IBAction func zoomIn 下，其中包含以下行：let region = MKCoordinateRegionMakeWithDistance(userLocation.location.coordinate, 2000, 2000)。由于某种原因，它给出了一个 nil 值。
【问题讨论】：
-
你没有分配
weak var mapView: MKMapView!。如果你想让它连接到插座，你可能没有这样做。 -
所以我必须将它连接到插座？我无法理解您的回答。