無法將類型“（）”的值轉換為預期的參數類型“字符串”

Question

我正在使用用戶輸入的郵政編碼，並將其轉換為城市名稱。 將其轉換為城市名稱后，我會將信息保存到Firebase數據庫中。 嘗試執行此操作時，出現錯誤“無法將類型'（）'的值轉換為預期的參數類型'字符串'”。 我從一個文本字段中獲取郵政編碼，並從以前的ViewController中傳遞它。 錯誤

 //first ViewController


 override func prepare(for segue: UIStoryboardSegue, sender: Any?)
{


    if let destination = segue.destination as? SignUpSecondViewController{

    destination.zipCode = zipCodeInput.text! 
    destination.name = nameText.text!
    destination.email = emailText.text!
    destination.password = passwordText.text!
    destination.pictureData = userImageView.image!
    }}

}

   //second ViewController

    var zipCode = String()

 func getLocationFromPostalCode(postalCode : String){
    let geocoder = CLGeocoder()

    geocoder.geocodeAddressString(postalCode) {
        (placemarks, error) -> Void in
        // Placemarks is an optional array of type CLPlacemarks, first item in array is best guess of Address

        if let placemark = placemarks?[0] {

            if placemark.postalCode == postalCode{
                // you can get all the details of place here
                print("\(placemark.locality)")
                print("\(placemark.country)")
            }
            else{
                print("Please enter valid zipcode")
            }
        }
    }
}




 @IBAction func completeButtonAction(_ sender: Any) {

let nameText = name
let emailField = email.lowercased()
let finalEmail = emailField.trimmingCharacters(in: .whitespacesAndNewlines)
let location = getLocationFromPostalCode(postalCode: zipCode)
let biography = bioTextView.text!
let passwordText = password
let interests = options.joined(separator: " , ")

    var pictureD: NSData?


    if let imageView = self.sentPic.image {
        pictureD = UIImageJPEGRepresentation(self.sentPic.image!, 0.70) as! NSData
    }


    if  finalEmail.isEmpty || biography.isEmpty || password.isEmpty || pictureD == nil {
        self.view.endEditing(true)
        let alertController = UIAlertController(title: "OOPS", message: " You must fill all the fields", preferredStyle: .alert)
        alertController.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: nil))
        present(alertController, animated: true, completion: nil)

    }else {
        SVProgressHUD.show()

        self.view.endEditing(true)
        authService.signUP(firstLastName: nameText, email: finalEmail, location: location, biography: biography, password: password, interests: interests, pictureData: pictureD as NSData!)

    }
    SVProgressHUD.dismiss()


    let storyboard = UIStoryboard(name: "Main", bundle: nil)
    let vc = storyboard.instantiateViewController(withIdentifier: "NewTabBarViewController") as! UIViewController
    // Alternative way to present the new view controller
     self.navigationController?.present(vc, animated: true, completion: nil)


}

Answer 1

您的問題從以下這一行開始：

let location = getLocationFromPostalCode(postalCode: zipCode)

問題是您的getLocationFromPostalCode沒有返回值，因此編譯器認為location的隱式類型是() ，這意味着沒有返回（void）類型的函數。

因此，從理論上講，您將需要更改：

func getLocationFromPostalCode(postalCode : String) {

至：

func getLocationFromPostalCode(postalCode : String) -> String {

並讓函數返回一個String值。

但是，您也不能這樣做，因為getLocationFromPostalCode的實現包括從異步網絡調用中獲取位置。

正確的解決方案是重寫該函數，以采用返回返回的位置的完成處理程序。

func getLocationFromPostalCode(postalCode: String, completion: (String?) -> Void) {
    let geocoder = CLGeocoder()

    geocoder.geocodeAddressString(postalCode) { (placemarks, error) -> Void in
        // Placemarks is an optional array of type CLPlacemarks, first item in array is best guess of Address

        if let placemark = placemarks?.first {
            if placemark.postalCode == postalCode {
                // you can get all the details of place here
                print("\(placemark.locality)")
                print("\(placemark.country)")
                completion(placemark.locality) // or whatever value you want
                return
            }
            else{
                print("Please enter valid zipcode")
            }
        }

        completion(nil) // no location found
    }
}

現在，所有這些都已修復，您需要重做如何獲取位置。

@IBAction func completeButtonAction(_ sender: Any) {
    var pictureD: Data? = nil
    if let imageView = self.sentPic.image {
        pictureD = UIImageJPEGRepresentation(imageView, 0.70)
    }

    let emailField = email.lowercased()
    let finalEmail = emailField.trimmingCharacters(in: .whitespacesAndNewlines)
    let biography = bioTextView.text!
    let passwordText = password

    if  finalEmail.isEmpty || biography.isEmpty || password.isEmpty || pictureD == nil {
        self.view.endEditing(true)
        let alertController = UIAlertController(title: "OOPS", message: " You must fill all the fields", preferredStyle: .alert)
        alertController.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: nil))
        present(alertController, animated: true, completion: nil)
    }else {
        getLocationFromPostalCode(postalCode: zipCode) { (location) in
            guard let location = location else {
                print("no location")
                return
            }

            let nameText = name
            let interests = options.joined(separator: " , ")

            SVProgressHUD.show()

            self.view.endEditing(true)
            authService.signUP(firstLastName: nameText, email: finalEmail, location: location, biography: biography, password: password, interests: interests, pictureData: pictureD!)
            SVProgressHUD.dismiss()
        }
    }

    let storyboard = UIStoryboard(name: "Main", bundle: nil)
    let vc = storyboard.instantiateViewController(withIdentifier: "NewTabBarViewController") as! UIViewController
    // Alternative way to present the new view controller
    self.navigationController?.present(vc, animated: true, completion: nil)
}