調用Web API時發生混淆錯誤

Question

我們有幾個SDK旨在使所有技能級別的開發人員儘可能簡單，包括最新手消費政府API（http://usdepartmentoflabor.github.io/DOLAPI/code.html#sdks）。我現在試圖在Swift上取得一個開始，我將在一個簡單的應用程序的上下文中開始使用它，它有一個目的：證明SDK的工作原理。

我遇到的麻煩是它崩潰的原因，我無法解釋（完整的來源是在https://github.com/MikePulsiferDOL/test-app）。

import Foundation 

protocol GovDataRequestProtocol { 
    func didCompleteWithError(errorMessage: String) 
    func didCompleteWithArray(results: NSArray) 
} 

class GovDataRequest { 

    var delegate: GovDataRequestProtocol? = nil 

    var activeRequests = Int[]() 
    var APIKey = "" 
    var APIHost = "" 
    var APIURL = "" 

    init(APIKey: String, APIHost: String, APIURL:String) { 
     self.APIKey = APIKey 
     self.APIHost = APIHost 
     self.APIURL = APIURL 
    } 


    func callAPIMethod (#method: String, arguments: Dictionary<String,String>, timeOut: Double) { 
     // Construct the base url based on the provided information 
     var url = APIHost + APIURL + "/" + method 
     // Start building the query string 
     var queryString = "" 

     // Where appropriate, add the key 
     switch APIHost { 
     case "http://api.dol.gov": 
      queryString = "?KEY=" + APIKey 
     case "http://api.census.gov", "http://pillbox.nlm.nih.gov": 
      queryString = "?key=" + APIKey 
     case "http://api.eia.gov", "http://developer.nrel.gov", "http://api.stlouisfed.org", "http://healthfinder.gov": 
      queryString = "?api_key=" + APIKey 
     case "http://www.ncdc.noaa.gov": 
      queryString = "?token=" + APIKey 
     default: 
      // do nothing for now 
      println("doing nothing for now") 
     } 

     //Construct the arguments part of the query string 
     for (argKey, argValue) in arguments { 
      switch APIHost { 
      case "http://api.dol.gov": 
       // DOL's V1 API has specific formatting requirements for arguments in the query string 
       switch argKey { 
       case "top", "skip", "select", "orderby", "filter": 
        queryString += "&$" + argKey + "=" + argValue 
       case "format", "query", "region", "locality", "skipcount": 
        queryString += "&" + argKey + "=" + argValue 
       default: 
        println("nothing to see here") 
       } 
      case "http://go.usa.gov": 
       // go.usa.gov requires that the apiKey be the 2nd argument 
       if countElements(queryString) == 0 { 
        queryString += "?" + argKey + "=" + argValue + "&apiKey=" + APIKey 
       } else { 
        queryString += "&" + argKey + "=" + argValue 
       } 
      default: 
       if countElements(queryString) == 0 { 
        queryString += "?" + argKey + "=" + argValue 
       } else { 
        queryString += "&" + argKey + "=" + argValue 
       } 
      } 

     } 

     //If there are arguments, append them to the url 
     if countElements(queryString) > 0 { 
      url += queryString 
     } 

     //DOT FMCSA requires that the key be placed at the end. 
     if APIHost == "https://mobile.fmcsa.dot.gov" { 
      if countElements(queryString) > 0 { 
       url += "&webKey=" + APIKey 
      } else { 
       url += "?webKey=" + APIKey 
      } 
     } 

     /* 
      ASSUMPTION: data retrieved is in JSON format. 
      TODO: consider situation when XML is received. 
     */ 

     // Send the request to the API and parse the JSON 
     var urlToPackage = url.stringByAddingPercentEscapesUsingEncoding(NSUTF8StringEncoding) 
     println(urlToPackage) 
     var urlToSend: NSURL = NSURL(string: urlToPackage) 
     var session = NSURLSession.sharedSession() 
     var request = NSMutableURLRequest(URL:urlToSend) 
     //request.setTimeoutInterval(timeOut) 
     request.addValue("application/json",forHTTPHeaderField:"Accept") 
     var task = session.dataTaskWithRequest(request, completionHandler: {data, response, error -> Void in 
      println("Task completed") 
      if(error) { 
       // if there is an error in the request, print it to the console 
       //self.delegate?.didCompleteWithError("Error, Will Robinson") 
       //println(error.localizedDescription) 
       println("oops!") 
      } 
      var err: NSError? 
      var jsonResult = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: &err) as NSDictionary 
      if(err?) { 
       // If there is an error parson JSON, print it to the console 
       NSLog ("Error parsing the JSON") 
      } 
      var results: NSArray = jsonResult["results"] as NSArray 
      self.delegate?.didCompleteWithArray(results) 
     }) 
     task.resume() 
    } 


} 

視圖控制器：

import UIKit 

class ViewController: UIViewController, GovDataRequestProtocol { 


    var firstRequest: GovDataRequest = GovDataRequest(APIKey: "", APIHost: "http://data.fcc.gov", APIURL: "/lpfmapi/rest/v1/lat/36") 
    //var firstRequest: GovDataRequest = GovDataRequest(APIKey: "", APIHost: "https://itunes.apple.com", APIURL: "/search") 

    override func viewDidLoad() { 
     super.viewDidLoad() 
     // Do any additional setup after loading the view, typically from a nib. 

     self.firstRequest.delegate = self 
     //var arguments = Dictionary<String, String>() 
     var arguments = ["format": "json", "secondchannel": "true"] 
     //var arguments = ["term": "Angry Birds", "media": "software"] 
     var timeOut = 60.0 
     firstRequest.callAPIMethod(method: "long/-119", arguments: arguments, timeOut: timeOut) 
     //firstRequest.callAPIMethod(method: "", arguments: arguments, timeOut: timeOut) 
    } 

    override func didReceiveMemoryWarning() { 
     super.didReceiveMemoryWarning() 
     // Dispose of any resources that can be recreated. 
    } 

    func didCompleteWithError (errorMessage: String) { 
     NSLog("error") 

    } 

    func didCompleteWithArray (results:NSArray) { 
     println("success!") 
     //Let's see what we've got 
     for item : AnyObject in results { 
      if let oneItem = item as? NSDictionary { 
       println("Dictionary!") 
      } else { 
       println("Not a Dictionary!") 
      } 

     } 

    } 
} 

當我使用iTunes的API來進行測試，它的工作原理。如果使用FCC，那麼它會在底部附近的代碼的錯誤處理部分崩潰（EXC_BAD_INSTRUCTION（code = EXCI386_INVOP，subcode = 0x0））。

如果我將錯誤處理代碼註釋掉，它會在發送請求的地方崩潰（在var任務...）。如您所見，我打印發送的URL（urlToPackage）。我將這個輸出結果輸入到chrome中，以驗證URL是否正確形成。

想法？

感謝

Answer 1

返回的JSON不會出現有results陣列，所以這行：

var results: NSArray = jsonResult["results"] as NSArray 

獲得零&炸燬。當我用有效密鑰替換results時，例如interferingAnalysis，您的示例代碼工作正常。