如何查詢並確保返回的值只添加到數組中？

Question

我有一個代碼，它運行通過palettes的所有孩子，並找出顏色十六進制是否與這些孩子中的任何值相匹配。如果匹配，它會從childByAutoID中提取URL，然後將其添加到數組中。

databaseRef.child("palettes").queryOrdered(byChild: "top").queryEqual(toValue: text).observeSingleEvent(of: .value, with: { (snapshot) in 

      if let snapDict = snapshot.value as? [String:AnyObject]{ 

       for each in snapDict as [String:AnyObject]{ 

        let _URL = each.value["URL"] as! String 
        self.arrayVar.append(_URL) // Turning it into an array. 

       } 
      } 
    }) 

     databaseRef.child("palettes").queryOrdered(byChild: "bottom").queryEqual(toValue: text).observeSingleEvent(of: .value, with: { (snapshot) in 

      if let snapDict = snapshot.value as? [String:AnyObject]{ 

       for each in snapDict as [String:AnyObject]{ 

        let _URL = each.value["URL"] as! String 
        self.arrayVar.append(_URL) // Turning it into an array. 

       } 
      } 

     }) 

     databaseRef.child("palettes").queryOrdered(byChild: "accessories").queryEqual(toValue: text).observeSingleEvent(of: .value, with: { (snapshot) in 

      if let snapDict = snapshot.value as? [String:AnyObject]{ 

       for each in snapDict as [String:AnyObject]{ 

        let _URL = each.value["URL"] as! String 
        self.arrayVar.append(_URL) // Turning it into an array. 

       } 
      } 

     }) 

     databaseRef.child("palettes").queryOrdered(byChild: "shoes").queryEqual(toValue: text).observeSingleEvent(of: .value, with: { (snapshot) in 

      if let snapDict = snapshot.value as? [String:AnyObject]{ 

       for each in snapDict as [String:AnyObject]{ 

        let _URL = each.value["URL"] as! String 
        self.arrayVar.append(_URL) // Turning it into an array. 

       } 
      } 
     }) 
    } 

然而，這樣做的問題是，當有相同childByAutoID內的兩個相似的價值觀，它會追加「網址」兩次。

這裏是我的JSON樹的例子：

{ 
    "palettes" : { 
    "-KTjfdgcwdkF5j3OWOg8" : { 
     "URL" : "test1", 
     "accessories" : "#000000", 
     "bottom" : "#2B676E", 
     "shoes" : "#000000", 
     "top" : "#274E64" 
    }, 
    "-KTji_7xUNu2PejD4Xz6" : { 
     "URL" : "test2", 
     "accessories" : "#2B6766", 
     "bottom" : "#2B676E", 
     "shoes" : "#000000", 
     "top" : "#274E64" 
    } 
    } 
} 

將返回[test1, test1, test2]時#000000等於text，當打印arrayVar。

如何確保URL只附加一次childByAutoID？例如，[test1, test2]在這種情況下。

Answer 1

您的數組轉換爲一個可變的字典，然後設置檢索爲重點，其價值布爾你的對象： -

var arrayVar = NSMutableDictionary() 
databaseRef.child("palettes").queryOrdered(byChild: "shoes").queryEqual(toValue: text).observeSingleEvent(of: .value, with: { (snapshot) in 

     if let snapDict = snapshot.value as? [String:AnyObject]{ 

      for each in snapDict as [String:AnyObject]{ 

       let _URL = each.value["URL"] as! String 
       self.arrayVar.setObject(true, forKey: _URL as NSCopying) 
      } 
     } 
    }) 

爲了讓您的網址只是： -

for eachUrl in arrayVar{ 

     let url = eachUrl.key 

    } 

導航通過字典比數組更有效率和關係，特別是在firebase中。