ios - 使用按钮 Swift 删除 map 图钉

Question

我正在开发一个小型 map 应用程序，我希望有一个按钮可以删除掉落到 map 上的所有图钉(内存)。

到目前为止，我有用于管理位置的代码:

// Location function
func locationManager(manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
    let location = locations.last
    let center = CLLocationCoordinate2D(latitude: location!.coordinate.latitude, longitude: location!.coordinate.longitude)
    let region = MKCoordinateRegion(center: center, span: MKCoordinateSpan(latitudeDelta: 0.004, longitudeDelta: 0.004))
    self.placesMap?.setRegion(region, animated: true)
    self.locationManager.stopUpdatingLocation()
    let locationDictionary:[String:Double] = ["latitude":center.latitude,"longitude":center.longitude]
    var locationArray = [[String:Double]]()
    if NSUserDefaults.standardUserDefaults().objectForKey("locationArray") != nil {
        locationArray = NSUserDefaults.standardUserDefaults().objectForKey("locationArray") as! [[String:Double]]
    }
    locationArray.append(locationDictionary)
    NSUserDefaults.standardUserDefaults().setObject(locationArray, forKey: "locationArray")
    NSUserDefaults.standardUserDefaults().synchronize()
}

func locationManager(manager: CLLocationManager, didFailWithError error: NSError)
{
    print("Error code: " + error.localizedDescription)
}

这是放置图钉的按钮:

@IBOutlet weak var addButton: UIBarButtonItem!
@IBAction func addButton(sender: AnyObject) {
    let annotation = MKPointAnnotation()
    annotation.coordinate = CLLocationCoordinate2D(latitude: self.placesMap.userLocation.coordinate.latitude, longitude: self.placesMap.userLocation.coordinate.longitude)
    self.placesMap.addAnnotation(annotation)
    self.locationManager.startUpdatingLocation()
}

这里是重置引脚的导出/ Action :

@IBAction func resetMemories(sender: AnyObject) {
    func removeStoredLocations(){
        NSUserDefaults.standardUserDefaults().removeObjectForKey("locationArray")
        NSUserDefaults.standardUserDefaults().synchronize()
        placesMap.removeAnnotations(placesMap.annotations)
    }
}

当我按下按钮时，当前没有发生错误，但图钉仍保留在 map 上:(

Answer 1

在您的resetMemories IBAction 中，您创建了一个嵌套函数removeStoredLocations。然后你永远不会调用那个嵌套函数，所以代码永远不会被执行。我建议去掉嵌套函数:

@IBAction func resetMemories(sender: AnyObject) 
{          
  NSUserDefaults.standardUserDefaults().removeObjectForKey("locationArray")
  NSUserDefaults.standardUserDefaults().synchronize()
  let annotationsToRemove = placesMap.annotations.filter 
  { 
    $0 !==  placesMap.userLocation 
  }
  placesMap.removeAnnotations( annotationsToRemove )
}

或者，如果你真的想要一个嵌套函数，你必须调用它:

@IBAction func resetMemories(sender: AnyObject) 
{
  //Define our local function removeStoredLocations().
  func removeStoredLocations()    
  {          
    NSUserDefaults.standardUserDefaults().removeObjectForKey("locationArray")
    NSUserDefaults.standardUserDefaults().synchronize()
    let annotationsToRemove = placesMap.annotations.filter 
    { 
      $0 !==  placesMap.userLocation 
    }
    placesMap.removeAnnotations( annotationsToRemove )
  }

  //Now that we've defined our local function, call it.
  removeStoredLocations()
}

编辑:

Jthomps 是对的。您应该使用他的代码，该代码不会删除用户位置的注释。我正在编辑上面的代码以合并他的代码。