json - 添加注释会导致在展开可选值时意外发现 nil

Question

目前正在使用 json 和 mapkit，从 json 获取经度和纬度。使用数组存储 json 结果，而不是使用 for 循环从数组中获取经度和纬度，如下所示

dispatch_async(dispatch_get_main_queue(), { () -> Void in
                UIApplication.sharedApplication().networkActivityIndicatorVisible = false
                var allContacts: AnyObject! = NSJSONSerialization.JSONObjectWithData(allContactsData!, options: NSJSONReadingOptions(0), error: nil)
                self.dataArray = allContacts as [AnyObject]

                for(self.i = 0; self.i < self.dataArray.count; self.i++){
                    println(self.dataArray[self.i])
                    var dict: NSDictionary = self.dataArray[self.i] as NSDictionary
                    self.crimeCat = dict["category"] as? String
                    self.crimeName = dict["name"] as? String
                    var crimeLat = dict["latitude"] as CLLocationDegrees //throws an error here
                    var crimeLong = dict["longitude"] as CLLocationDegrees
                    //println(self.crimeName)

                    var crimeLocation:CLLocationCoordinate2D = CLLocationCoordinate2DMake(crimeLat,crimeLong)
                    var annotation = MKPointAnnotation()
                    annotation.coordinate = crimeLocation
                    annotation.title = self.crimeCat!
                    self.map.addAnnotation(annotation)
                }
                println(allContacts)

但是每当我运行应用程序时我得到

fatal error: unexpectedly found nil while unwrapping an Optional value

我添加了断点，细节似乎加载正确

以下是我尝试过的方法

self.crimeLat = dict["latitude"] as? CLLocationDegrees
self.crimeLong = dict["longitude"] as? CLLocationDegrees


var crimeLocation:CLLocationCoordinate2D = CLLocationCoordinate2DMake(self.crimeLat,self.crimeLong) //when i try this method i get same error here

我知道返回的结果有纬度和经度，因为我已经测试过了。

任何建议我可能做错了什么？谢谢

Answer 1

正如 lchamp 所说，我提取 json 数据的方式不正确，返回了 json

location{
  latitude = "somevalue"
  longitude = "somevalue"
}

我修改了下面的代码

self.crimeLat = dict["latitude"] as? CLLocationDegrees
self.crimeLong = dict["longitude"] as? CLLocationDegrees

到

 self.crimeLat = ((dict["location"] as NSDictionary)["latitude"] as NSString).doubleValue
 self.crimeLong = ((dict["location"] as NSDictionary)["longitude"] as NSString).doubleValue

现在已经解决了这个问题。