Question

我有一个代码，它通过palettes的所有子项运行，并查明颜色十六进制是否与这些子项中的任何值匹配。如果匹配，则会从childByAutoID中提取网址，然后将其添加到数组中。

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，问题在于，当同一childByAutoID内有两个相似的值时，它会附加＆＃39; URL＆＃39;两次。

这是我的JSON树的一个例子：

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

当[test1, test1, test2]等于#000000且打印text时，会返回arrayVar。

如何确保每childByAutoID只附加一次网址？例如，在此实例中为[test1, test2]。

Answer 1

将您的数组转换为可变字典，然后将您检索的对象设置为键及其值布尔值： -

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)
            }
        }
    })

要获取您的网址： -

 for eachUrl in arrayVar{

      let url = eachUrl.key

     }

浏览字典比数组更有效和关系，特别是在firebase中。

如何查询并确保返回的值仅添加到数组一次？

1 个答案: