使用未解決的標識符swift 3.0

Question

我想從php中取出一個json數組，並將其保存爲xcode中的一個數組來處理。我能夠拉動json數據並在xcode終端中打印它，但出於某種原因，我可以'參考數組而不會出錯。這是我的代碼！

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

    //connect to website 
    let url = URL(string:"******") 
    let task = URLSession.shared.dataTask(with: url!) { (data, response, error) in 
     if error != nil 
     { 
      print("error") 
     } 
     else 
     { 
      if let content = data 
      { 
       do 
       { 
        //download JSON data from php page, display data 
        let SongArray = try JSONSerialization.jsonObject(with: content, options: JSONSerialization.ReadingOptions.mutableContainers) as Any 
        print(SongArray) 
       } 
       catch 
       { 

       } 
      } 
     } 
    } 
    task.resume() 

    //Make buttons 

    var buttonY: CGFloat = 20 
    for song in SongArray { 
     let SongButton = UIButton(frame: CGRect(x, 50, y: buttonY, width, 250, height: 30)) 

    } 

} //close viewDidLoad 

我得到一個錯誤，當我遍歷SongArray

它說： '未解決的標識符的使用 「SongArray」'。即使我'讓'它存在之前..

Answer 1

您的代碼不會有幾個原因的工作：

• 你會得到編譯器錯誤因爲你忽略了實際的類型。如果您知道這是一個更具體的類型，則Any始終是最糟糕的解決方案。
• URLSession異步工作，song循環將永遠不會執行。你必須把它到完成塊

---

根據給定的JSON對象是String數組的數組。

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

    //connect to website 
    let url = URL(string:"******") 
    let task = URLSession.shared.dataTask(with: url!) { (data, response, error) in 
     if error != nil { 
      print("error:", error!) 
     } 
     else { 

      do { 
       //download JSON data from php page, display data 
       let songArray = try JSONSerialization.jsonObject(with: data!, options: []) as! [[String]] 
       print(songArray) 
       //Make buttons 

       var buttonY: CGFloat = 20 
       for song in songArray { 
        let songButton = UIButton(frame: CGRect(x: 50, y: buttonY, width: 250, height: 30)) 
       } 
      } 
      catch { 
       print(error) 
      } 
     } 
    } 
    task.resume() 

} //close viewDidLoad 

正如在問題解決神奇的use of unresolved identifier錯誤的副作用。

Answer 2

因爲SongArray是在dataTask封閉，超出範圍。 你可以做這樣的事情：

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

    //connect to website 
    var SongArray: Any 
    let url = URL(string:"******") 
    let task = URLSession.shared.dataTask(with: url!) { (data, response, error) in 
     if error != nil 
     { 
      print("error") 
     } 
     else 
     { 
      if let content = data 
      { 
       do 
       { 
        //download JSON data from php page, display data 
        SongArray = try JSONSerialization.jsonObject(with: content, options: JSONSerialization.ReadingOptions.mutableContainers) as Any 
        print(SongArray) 
       } 
       catch 
       { 

       } 
      } 
     } 
    } 
    task.resume() 

    //Make buttons 

    var buttonY: CGFloat = 20 
    for song in SongArray { 
     let SongButton = UIButton(frame: CGRect(x, 50, y: buttonY, width, 250, height: 30)) 

    } 

} 

Answer 3

答案是評論的組合製成

//connect to website 
    var SongArray: Array<Any> 
    let url = URL(string:"http://cgi.soic.indiana.edu/~team22/SongData.php") 
    let task = URLSession.shared.dataTask(with: url!) { (data, response, error) in 
     if error != nil 
     { 
      print("error") 
     } 
     else 
     { 
      if let content = data 
      { 
       do 
       { 
        //download JSON data from php page, display data 
        let SongArray = try JSONSerialization.jsonObject(with: content, options: JSONSerialization.ReadingOptions.mutableContainers) as Any 
        print(SongArray) 
       } 
       catch 
       { 

       } 
      } 
     } 
    } 
    task.resume() 

    //Make buttons 

    var buttonY: CGFloat = 20 
    for song in SongArray {