无法在 Swift 2 中将“__NSCFNumber”类型的值转换为“NSString”

Posted 2023-03-05

【中文标题】无法在 Swift 2 中将“__NSCFNumber”类型的值转换为“NSString”

【英文标题】：Could not cast value of type '__NSCFNumber' to 'NSString' in Swift 2

【发布时间】：2016-06-02 12:29:45

【问题描述】：

我正在使用 CLLocationmanager 从应用程序委托中获取纬度和经度 通过使用以下代码：

  class AppDelegate: UIResponder, UIApplicationDelegate, CLLocationManagerDelegate


    var window: UIWindow?

    var locationManager: CLLocationManager!
    var seenError : Bool = false
    var locationFixAchieved : Bool = false
    var locationStatus : NSString = "Not Started"


    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool 
    initLocationManager();
        return true
    

    func initLocationManager() 
        seenError = false
        locationFixAchieved = false
        locationManager = CLLocationManager()
        locationManager.delegate = self
        CLLocationManager.locationServicesEnabled()
        locationManager.desiredAccuracy = kCLLocationAccuracyBest

        locationManager.requestAlwaysAuthorization()
        locationManager.startUpdatingLocation()
    

    func locationManager(manager: CLLocationManager!, didFailWithError error: NSError!) 
        locationManager.stopUpdatingLocation()
        if ((error) != nil) 
            if (seenError == false) 
                seenError = true
                print(error)
            
        
    

    func locationManager(manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) 
        if (locationFixAchieved == false) 
            locationFixAchieved = true
            var locationArray = locations as NSArray
            var locationObj = locationArray.lastObject as! CLLocation
            var coord = locationObj.coordinate
            NSUserDefaults.standardUserDefaults().setObject(coord.latitude, forKey: "latitude")



            NSUserDefaults.standardUserDefaults().setObject(coord.longitude, forKey: "longitude")
            NSUserDefaults.standardUserDefaults().synchronize()
            print(coord.latitude)
            print(coord.longitude)
        
    

通过使用代码在地图视图中使用 nsuserdefaults 中的值时

   latitude = (NSUserDefaults.standardUserDefaults().objectForKey("latitude") as? NSString)! as String
        longitude = (NSUserDefaults.standardUserDefaults().objectForKey("longitude") as? NSString)! as String
        let latitude1 = (latitude as NSString).doubleValue
        let longitude1 = (longitude as NSString).doubleValue
        let location = CLLocationCoordinate2D(
            latitude: latitude1,
            longitude: longitude1
        )

latitude = (NSUserDefaults.standardUserDefaults().objectForKey("latitude") as? NSString)! as String 处出现错误“无法将类型 '__NSCFNumber' (0x1944fb9f8) 的值转换为 'NSString'”

【问题讨论】：

coord.latitude 是 double，而不是 string。因此，当您将其保存到 NSUserDefaults 时，它会转换为 NSNumber。所以这应该可以解决问题：let latitude1 = (latitude as NSNumber).doubleValue

您将值保存为数字并尝试将其读回字符串。到底是什么问题？

感谢问题已解决..

【参考方案1】：

在 AppDelegate 中使用此代码将纬度和经度保存在 NSUserDefaults 中，如下所示

func locationManager(manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) 
    if (locationFixAchieved == false) 
        locationFixAchieved = true
        let locationArray = locations as NSArray
        let locationObj = locationArray.lastObject as! CLLocation
        let coord = locationObj.coordinate
        NSUserDefaults.standardUserDefaults().setDouble(coord.latitude, forKey: "latitude")
        NSUserDefaults.standardUserDefaults().setDouble(coord.longitude, forKey: "longitude")
        NSUserDefaults.standardUserDefaults().synchronize()
        print(coord.latitude)
        print(coord.longitude)
    

为了获取值，请在 viewcontroller 文件中使用此代码

 override func viewDidLoad() 
    super.viewDidLoad()

    // Do any additional setup after loading the view.
    let latitude2 = NSUserDefaults.standardUserDefaults().objectForKey("latitude")
    let longitude2 = NSUserDefaults.standardUserDefaults().objectForKey("longitude")
    let latitude1  = latitude2!.doubleValue
    let longitude1 = longitude2!.doubleValue
    let location = CLLocationCoordinate2D(
        latitude: latitude1,
        longitude: longitude1
    )

【参考方案2】：

NSUserDefaults.standardUserDefaults().objectForKey("longitude") 是一个 NSNumber，所以你只需要这样做：

let latitude = NSUserDefaults.standardUserDefaults().objectForKey("latitude")
let longitude = NSUserDefaults.standardUserDefaults().objectForKey("longitude")
    let latitude1 = latitude.doubleValue
    let longitude1 = longitude.doubleValue

更多，首先你可以像这样设置用户默认值

let latitude: CLLocationDegrees = 1.0
NSUserDefaults.standardUserDefaults().setDouble("latitude", forKey: "latitude") 

【讨论】：

它显示Cannot assign value of type 'AnyObject?'输入“字符串”