我将该类链接到我系统上的新用户注册。

class ProfileNewAddressViewController: UIViewController, UIPickerViewDataSource, UIPickerViewDelegate {

  // MARK: Properties
  @IBOutlet weak var streetTextField: UITextField!
  @IBOutlet weak var streetComplementTextField: UITextField!
  @IBOutlet weak var zipCodeTextField: UITextField!
  @IBOutlet weak var stateTextField: UITextField!
  @IBOutlet weak var countryTextField: UITextField!

  @IBAction func saveNewAddressPressed(sender: UIButton) {
  }

  var countries:[String]  = []

  let countriesPicker = UIPickerView()

  func populateCountries() {
    countries = RestApiManager.sharedInstance.getCountries()!
    countriesPicker.reloadAllComponents()
  }

  override func viewDidLoad() {
    super.viewDidLoad()

    populateCountries()

    countriesPicker.delegate = self
    countriesPicker.dataSource = self
    countryTextField.inputView = countriesPicker

  }

  func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int {
    return 1
  }

  func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {

      return countries.count

  }

  func pickerView(pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int)
  {

      return countryTextField.text = countries[row]
  }

  func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
      return countries[row]
  }

在这段代码中，我调用下面列出的函数 getCountries:

func getCountries() -> [String]? {
    var countries:[String] = []

    makeHTTPGetRequest(baseURL + "countries", parameters: ["page_size": "0"], completionHandler: { (data, response, error) in
      let data = data

      do {
        let jsonResult:NSArray = try NSJSONSerialization.JSONObjectWithData(data!, options:[]) as! NSArray
        for var i = 0; i < jsonResult.count; ++i {
          var countriesDict = jsonResult.objectAtIndex(i) as! NSDictionary
          countries.append(countriesDict["title"] as! String)
        }
      }

      catch {
        print("Error: \(error)")
      }
    })
    return countries
  }

调用 HTTP GET:

private func makeHTTPGetRequest(path: String, parameters: [String: AnyObject], completionHandler: (NSData?, NSURLResponse?, NSError?) -> Void) -> NSURLSessionTask {
    let parameterString = parameters.stringFromHttpParameters()
    let requestURL = NSURL(string:"\(path)?\(parameterString)")!

    let request = NSMutableURLRequest(URL: requestURL)
    request.HTTPMethod = "GET"
    //request.setValue("Bearer " + userInfoDefaults.stringForKey("accessToken")!, forHTTPHeaderField: "Authorization")
    request.setValue("Bearer diU8PIBuGHHlvD5PKstRDRbHdCEMxpb5", forHTTPHeaderField: "Authorization")

    let session = NSURLSession.sharedSession()
    let task = session.dataTaskWithRequest(request, completionHandler:completionHandler)
    task.resume()

    return task
  }

出于某种原因，我的 pickerView 没有在屏幕上显示任何值。我已经调试了代码并注意到国家数组正在填充正确的值。我需要以任何方式重新加载某些组件才能正常工作吗？

最佳答案

看起来您在完成处理程序期间正在后台填充国家/地区。该代码在完成网络调用之前不会填充国家/地区数组，但您会立即重新加载选择器。我建议在填充数组后调用 getCountries 函数内的 lickers reloadAllComponents，但看起来该调用在另一个对象中，因此可能会在填充数组后调用的 getCountries 函数中添加一个回调(完成处理程序)。您必须从主线程调用选择器的 reloadAllComponents。

  func populateCountries() {
          countries = RestApiManager.sharedInstance.getCountries!({
              dispatch_async(dispatch_get_main_queue()){ 
                  countriesPicker.reloadAllComponents() 
          })
      }
  }

那么getCountries可以是这个

func getCountries(handler:()->Void) -> [String]? {
    var countries:[String] = []

    makeHTTPGetRequest(baseURL + "countries", parameters: ["page_size": "0"], completionHandler: { (data, response, error) in
      let data = data

      do {
          let jsonResult:NSArray = try  NSJSONSerialization.JSONObjectWithData(data!, options:[]) as! NSArray
          for var i = 0; i < jsonResult.count; ++i {
              var countriesDict = jsonResult.objectAtIndex(i) as! NSDictionary
              countries.append(countriesDict["title"] as! String)
          }
       }

       catch {
          print("Error: \(error)")
       }
       handler()
   })
   return countries
}

关于ios - Swift (iOS) - PickerView 未被 HTTP GET 请求填充，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/37138889/