Question

我尝试显示单元格内帖子创建者与当前用户之间的距离。

我的错误是

无法转换“字符串”类型的值？预期的参数类型“ CLLocationDegrees”（又称“ Double”）

在以下代码中：

func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
    if let lastLocation = locations.last {
        let geoCoder = CLGeocoder()

        let myLocation = CLLocation(latitude: lastLocation.coordinate.latitude, longitude: lastLocation.coordinate.longitude)

/*Here the error*/ let myBuddysLocation = CLLocation(latitude: job!.distance, longitude: job!.distance)

        let distance = myLocation.distance(from: myBuddysLocation) / 1000
        print(String(format: "The distance to my buddy is %.01fkm", distance))
    }
}

这是我的JobClass：

class Job {

var distance: String?
let ref: DatabaseReference!

init(distance: String? = nil) {
    self.distance = distance
    ref = Database.database().reference().child("jobs").childByAutoId()
}

init(snapshot: DataSnapshot){
    ref = snapshot.ref
    if let value = snapshot.value as? [String : Any] {
        distance = value["distance"] as? String
    }
}

func save() {
    let newPostKey = ref.key
            let postDictionary = [
                "distance" : self.distance!
                ] as [String : Any]
            self.ref.setValue(postDictionary)
}
}

我希望有人知道如何解决它，如果您愿意的话，我可以添加更多代码//我是编码新手

Answer 1

这很正常，因为距离应为Double值。将其更改为：var distance: Double?应该更正它。或将值解析为Double let myBuddysLocation = CLLocation(latitude: Double(distance)!, longitude: Double(distance)!)

我建议您避免使用!，因为如果字符串不是数字，则它可能会产生致命错误，您可以使用guard来保护值，或者让它像下面的示例一样：

if let latitude = Double(distance) {
    let myBuddysLocation = CLLocation(latitude: latitude, longitude: latitude)
}

Answer 2

实际上，在您的函数中，唯一的问题是您需要传递字符串值来代替double，而您需要像这样进行更改。

let myBuddysLocation = CLLocation(latitude: Double.init(job!.distance) ?? 0.0, longitude: Double.init(job!.distance) ?? 0.0)

您需要像这样更改功能

func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
    if let lastLocation = locations.last {
        let geoCoder = CLGeocoder()

        let myLocation = CLLocation(latitude: lastLocation.coordinate.latitude, longitude: lastLocation.coordinate.longitude)

        let myBuddysLocation = CLLocation(latitude: Double.init(job!.distance) ?? 0.0, longitude: Double.init(job!.distance) ?? 0.0) 

        let distance = myLocation.distance(from: myBuddysLocation) / 1000
        print(String(format: "The distance to my buddy is %.01fkm", distance))
    }
}

Answer 3

错误是不言自明的：您试图设置String?而不是CLLocationDegrees，但是甚至可以使用Double类型。

有几种解决方法：

1）您可以按照以下步骤更改类定义：

   class Job {

          // Change distance to Double and set a default value instead of optional
          var distance: Double = 0.0
          let ref: DatabaseReference!

          // Change the init
          init(distance: Double = 0.0) {
              self.distance = distance
              ref = Database.database().reference().child("jobs").childByAutoId()
          }

          //You have to change all your distance to Double
          init(snapshot: DataSnapshot){
              ref = snapshot.ref
              if let value = snapshot.value as? [String : Any] {
                 // So change this cast
                  distance = value["distance"] as Double
              }
          }
         }

2）您可以尝试从 String？转换为 Double ，但是我不建议这样做。

无论如何，这是您可以执行的操作：

   if let dist = Double(job!.distance){
          let myBuddysLocation = CLLocation(latitude: dist, longitude: dist) -> Error Appears in this Line

           let distance = myLocation.distance(from: myBuddysLocation) / 1000
           print(String(format: "The distance to my buddy is %.01fkm", distance))
   }

无法转换类型为'String'的值？到预期的参数类型“ CLLocationDegrees”（又名“ Double”）

3 个答案: