JSON Swift 3 CTA Train Trackerの構文解析

Question

CTAの列車到着のJSONを解析しようとしています。私ViewController.swift

import UIKit 

class ViewController: UIViewController { 

override func viewDidLoad() { 
    super.viewDidLoad() 

    let url = URL(string: "http://lapi.transitchicago.com/api/1.0/ttarrivals.aspx?key=individualkeygoeshere&mapid=41320&outputType=JSON") 

    let task = URLSession.shared.dataTask(with: url!) { (data, response, error) in 
     if error != nil 
     { 
      print("Error") 
     } 
     else { 
      if let content = data 
      { 
       do { 
        let myJSON = try JSONSerialization.jsonObject(with: content, options: JSONSerialization.ReadingOptions.mutableContainers) as AnyObject 

        if let ctattimetable = myJSON["ctatt"] as? [String:Any] { 
         if let estArrivalTime = ctattimetable["eta"] as? [Any] { 
          print(estArrivalTime) 
          if let stationName = estArrivalTime["staNm"] { 
           print(stationName) 
          } 
         } 
        } 
       } 
       catch { 
       } 
      } 
     } 
    } 
    task.resume() 
} 

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

で

{ 
ctatt =  { 
    errCd = 0; 
    errNm = "<null>"; 
    eta =   (
        { 
      arrT = "2017-05-15T23:22:32"; 
      destNm = Howard; 
      destSt = 30173; 
      flags = "<null>"; 
      heading = 305; 
      isApp = 0; 
      isDly = 0; 
      isFlt = 0; 
      isSch = 0; 
      lat = "41.91065"; 
      lon = "-87.64918"; 
      prdt = "2017-05-15T23:18:32"; 
      rn = 843; 
      rt = Red; 
      staId = 41320; 
      staNm = Belmont; 
      stpDe = "Service toward Howard"; 
      stpId = 30255; 
      trDr = 1; 
     }, 
        { 
      arrT = "2017-05-15T23:21:45"; 
      destNm = "95th/Dan Ryan"; 
      destSt = 30089; 
      flags = "<null>"; 
      heading = 91; 
      isApp = 0; 
      isDly = 0; 
      isFlt = 0; 
      isSch = 0; 
      lat = "41.95377"; 
      lon = "-87.65493"; 
      prdt = "2017-05-15T23:17:45"; 
      rn = 836; 
      rt = Red; 
      staId = 41320; 
      staNm = Belmont; 
      stpDe = "Service toward 95th/Dan Ryan"; 
      stpId = 30256; 
      trDr = 5; 
     }, 
        { 
      arrT = "2017-05-15T23:27:28"; 
      destNm = Kimball; 
      destSt = 30249; 
      flags = "<null>"; 
      heading = 357; 
      isApp = 0; 
      isDly = 0; 
      isFlt = 0; 
      isSch = 0; 
      lat = "41.90563"; 
      lon = "-87.63712"; 
      prdt = "2017-05-15T23:18:28"; 
      rn = 426; 
      rt = Brn; 
      staId = 41320; 
      staNm = Belmont; 
      stpDe = "Service toward Kimball or Linden"; 
      stpId = 30257; 
      trDr = 1; 
     }, 
        { 
      arrT = "2017-05-15T23:27:16"; 
      destNm = Loop; 
      destSt = 30249; 
      flags = "<null>"; 
      heading = 89; 
      isApp = 0; 
      isDly = 0; 
      isFlt = 0; 
      isSch = 0; 
      lat = "41.96641"; 
      lon = "-87.67864"; 
      prdt = "2017-05-15T23:18:16"; 
      rn = 427; 
      rt = Brn; 
      staId = 41320; 
      staNm = Belmont; 
      stpDe = "Service toward Loop"; 
      stpId = 30258; 
      trDr = 5; 
     }, 
        { 
      arrT = "2017-05-15T23:28:25"; 
      destNm = "95th/Dan Ryan"; 
      destSt = 30089; 
      flags = "<null>"; 
      heading = 178; 
      isApp = 0; 
      isDly = 0; 
      isFlt = 0; 
      isSch = 0; 
      lat = "41.97345"; 
      lon = "-87.65853"; 
      prdt = "2017-05-15T23:18:25"; 
      rn = 939; 
      rt = Red; 
      staId = 41320; 
      staNm = Belmont; 
      stpDe = "Service toward 95th/Dan Ryan"; 
      stpId = 30256; 
      trDr = 5; 
     }, 
        { 
      arrT = "2017-05-15T23:32:01"; 
      destNm = Howard; 
      destSt = 30173; 
      flags = "<null>"; 
      heading = 357; 
      isApp = 0; 
      isDly = 0; 
      isFlt = 0; 
      isSch = 0; 
      lat = "41.87815"; 
      lon = "-87.6276"; 
      prdt = "2017-05-15T23:18:01"; 
      rn = 928; 
      rt = Red; 
      staId = 41320; 
      staNm = Belmont; 
      stpDe = "Service toward Howard"; 
      stpId = 30255; 
      trDr = 1; 
     }, 
        { 
      arrT = "2017-05-15T23:37:32"; 
      destNm = "95th/Dan Ryan"; 
      destSt = 30089; 
      flags = "<null>"; 
      heading = 162; 
      isApp = 0; 
      isDly = 0; 
      isFlt = 0; 
      isSch = 0; 
      lat = "42.00566"; 
      lon = "-87.66565"; 
      prdt = "2017-05-15T23:18:32"; 
      rn = 926; 
      rt = Red; 
      staId = 41320; 
      staNm = Belmont; 
      stpDe = "Service toward 95th/Dan Ryan"; 
      stpId = 30256; 
      trDr = 5; 
     }, 
        { 
      arrT = "2017-05-15T23:40:41"; 
      destNm = Kimball; 
      destSt = 0; 
      flags = "<null>"; 
      heading = "<null>"; 
      isApp = 0; 
      isDly = 0; 
      isFlt = 0; 
      isSch = 1; 
      lat = "<null>"; 
      lon = "<null>"; 
      prdt = "2017-05-15T23:18:41"; 
      rn = 431; 
      rt = Brn; 
      staId = 41320; 
      staNm = Belmont; 
      stpDe = "Service toward Kimball or Linden"; 
      stpId = 30257; 
      trDr = 1; 
     }, 
        { 
      arrT = "2017-05-15T23:40:41"; 
      destNm = "See train"; 
      destSt = 0; 
      flags = "<null>"; 
      heading = "<null>"; 
      isApp = 0; 
      isDly = 0; 
      isFlt = 0; 
      isSch = 1; 
      lat = "<null>"; 
      lon = "<null>"; 
      prdt = "2017-05-15T23:18:41"; 
      rn = 434; 
      rt = Brn; 
      staId = 41320; 
      staNm = Belmont; 
      stpDe = "Service toward Loop"; 
      stpId = 30258; 
      trDr = 5; 
     } 
    ); 
    tmst = "2017-05-15T23:18:54"; 
}; 
} 

私はちょうどSwift 3でJSONを解析まわりで私の頭を取得しようと、まだ特定の目標を持っていません。だから、私がこの場合にしようとしているのは、各ηのステーション名（JSON内のstaNm）を取得することなので、基本的に私はBelmontをレスポンスとして取得しようとしています。私は迅速なコンパイラエラーを取得できません '[任意]型の値に' String '型のインデックスを添字できません。私はηから各キーの値を取得する方法について固まっています。どのように私はこれを行うだろう誰も考えている？ CTA列車トラッカーAPIのドキュメントはここにある：http://www.transitchicago.com/developers/ttdocs/default.aspx

Answer 1

etaはDictionaryの配列であり、配列はそれから特定のキーにアクセスしたい場合は、単にループする必要があり、あなたがIntで配列に添字ができsubscriptStringとタイプすることはできません配列の代わりにAnyという配列を指定する代わりに、辞書の配列として指定する必要があります。

do { 
    let myJSON = try JSONSerialization.jsonObject(with: content, options: []) as? [String:Any] ?? [:] 

    if let ctattimetable = myJSON["ctatt"] as? [String:Any] { 
     if let estArrivalTime = ctattimetable["eta"] as? [[String:Any]] { 
      for item in estArrivalTime { 
       if let stationName = item["staNm"] as? String { 
        print(stationName) 
       } 
       //You can access other keys here on item dictionary same way like staNm 
      } 
     } 
    } 
} 
catch { 
} 

Answer 2

• JSON辞書ではなく、キーetaため何

  let myJSON = try JSONSerialization.jsonObject(with: content) as! [String:Any] 
  

• 値は、辞書の配列よりもむしろ何

  if let estArrivalTime = ctattimetable["eta"] as? [[String:Any]] 
  

  のアレイであります

• さらに、キーstaNmの値を出力するだけでなく、キャストする必要がある場合はStringになります。

さらに具体的にすると、コンパイラは不平を言わないでしょう。

いつものように、Swiftでは.mutableContainersを使用しないでください。それは全く効果がありません。

スウィフトブログでの総合的なアップルの記事をお読みください：Working with JSON in Swift

Answer 3

if let ctattimetable = myJSON["ctatt"] as? [String : Any] { 
      if let estArrivalTime = ctattimetable["eta"] as? [[String : Any]] { 
       for eta in estArrivalTime { 
        if let stationName = eta["staNm"] { 
         print(stationName) 
        } 
       } 
      } 
     } 

あなたがこの許可すれば声明からのオブジェクトの配列を取得しているため、この声明

if let stationName = estArrivalTime["staNm"] 

に間違っている

Answer 4

if let estArrivalTime = ctattimetable["eta"] as? [Any] 

だからあなたのチ内のすべてのアイテムを反復処理する必要がありますsの配列は、このループ

for item in estArrivalTime { 
       if let _staNm = item["staNm"] as? String { 
        print("staNm : \(_staNm)") 
       } 

      }