Ios 使用函数从swift字典中动态删除空值

我有下面的字典代码

var dic : [String: AnyObject] = ["FirstName": "Anvar", "LastName": "Azizov", "Website": NSNull(),"About": NSNull()]

 func removeNSNull(from dict: [String: Any]) -> [String: Any] {
    var mutableDict = dict
    let keysWithEmptString = dict.filter { $0.1 is NSNull }.map { $0.0 }
    for key in keysWithEmptString {
        mutableDict[key] = ""
    }
    return mutableDict
}

我已经使用下面的代码删除了具有空值的键

var keys = dic.keys.array.filter({dic[$0] is NSNull})
for key in keys {
  dic.removeValueForKey(key)
}

它适用于静态字典，但我希望动态执行，我希望使用函数执行，但每当我将字典作为参数传递时，它将作为let-means常量执行，因此无法删除null键 我做了下面的代码

func nullKeyRemoval(dic : [String: AnyObject]) -> [String: AnyObject]{
        var keysToRemove = dic.keys.array.filter({dic[$0] is NSNull})
        for key in keysToRemove {
            dic.removeValueForKey(key)
        }
        return dic
}

---

请告诉我这个

的解决方案，而不是使用一个全局函数（或一个方法），为什么不使用一个扩展名将它变成一个

字典

的方法呢

extension Dictionary {
    func nullKeyRemoval() -> Dictionary {
        var dict = self

        let keysToRemove = Array(dict.keys).filter { dict[$0] is NSNull }
        for key in keysToRemove {
            dict.removeValue(forKey: key)
        }

        return dict
    }
}

   extension NSDictionary
    {
        func RemoveNullValueFromDic()-> NSDictionary
        {
            let mutableDictionary:NSMutableDictionary = NSMutableDictionary(dictionary: self)
            for key in mutableDictionary.allKeys
            {
                if("\(mutableDictionary.objectForKey("\(key)")!)" == "<null>")
                {
                    mutableDictionary.setValue("", forKey: key as! String)
                }
                else if(mutableDictionary.objectForKey("\(key)")!.isKindOfClass(NSNull))
                {
                    mutableDictionary.setValue("", forKey: key as! String)
                }
                else if(mutableDictionary.objectForKey("\(key)")!.isKindOfClass(NSDictionary))
                {
                    mutableDictionary.setValue(mutableDictionary.objectForKey("\(key)")!.RemoveNullValueFromDic(), forKey: key as! String)
                }
            }
            return mutableDictionary
        }
    }

它适用于任何泛型类型（因此不限于

String，AnyObject

），您可以直接从字典本身调用它：

var dic : [String: AnyObject] = ["FirstName": "Anvar", "LastName": "Azizov", "Website": NSNull(),"About": NSNull()]
let dicWithoutNulls = dic.nullKeyRemoval()

---

与其使用全局函数（或方法），为什么不使用扩展将其作为字典的方法呢

extension Dictionary {
    func nullKeyRemoval() -> Dictionary {
        var dict = self

        let keysToRemove = Array(dict.keys).filter { dict[$0] is NSNull }
        for key in keysToRemove {
            dict.removeValue(forKey: key)
        }

        return dict
    }
}

   extension NSDictionary
    {
        func RemoveNullValueFromDic()-> NSDictionary
        {
            let mutableDictionary:NSMutableDictionary = NSMutableDictionary(dictionary: self)
            for key in mutableDictionary.allKeys
            {
                if("\(mutableDictionary.objectForKey("\(key)")!)" == "<null>")
                {
                    mutableDictionary.setValue("", forKey: key as! String)
                }
                else if(mutableDictionary.objectForKey("\(key)")!.isKindOfClass(NSNull))
                {
                    mutableDictionary.setValue("", forKey: key as! String)
                }
                else if(mutableDictionary.objectForKey("\(key)")!.isKindOfClass(NSDictionary))
                {
                    mutableDictionary.setValue(mutableDictionary.objectForKey("\(key)")!.RemoveNullValueFromDic(), forKey: key as! String)
                }
            }
            return mutableDictionary
        }
    }

扩展字典 { func RemoveNullValueFromDic（）->NSDictionary { 让mutableDictionary:NSMutableDictionary=NSMutableDictionary（dictionary:self） 用于mutableDictionary.allKeys中的键 { 如果（“\（mutableDictionary.objectForKey（“\（key）”）！”==“”） { mutableDictionary.setValue（“，forKey:key as！String） } else if（mutableDictionary.objectForKey（“\（key）”）！.iskindof类（NSNull）） { mutableDictionary.setValue（“，forKey:key as！String） } else if（mutableDictionary.objectForKey（“\（key）”）！.iskindof类（NSDictionary）） { mutableDictionary.setValue（mutableDictionary.objectForKey（“\（key）”）！.RemoveNullValueFromDic（），forKey:key as！String） } } 返回可变字典 } }

---

对于

Swift 3.0/3.1

，这可能会有所帮助。还删除递归对象

NSNull

：

extension Dictionary {
    func nullKeyRemoval() -> [AnyHashable: Any] {
        var dict: [AnyHashable: Any] = self

        let keysToRemove = dict.keys.filter { dict[$0] is NSNull }
        let keysToCheck = dict.keys.filter({ dict[$0] is Dictionary })
        for key in keysToRemove {
            dict.removeValue(forKey: key)
        }
        for key in keysToCheck {
            if let valueDict = dict[key] as? [AnyHashable: Any] {
                dict.updateValue(valueDict.nullKeyRemoval(), forKey: key)
            }
        }
        return dict
    }
}

---

Swift 3+：从字典中删除空值

var dic : [String: AnyObject] = ["FirstName": "Anvar", "LastName": "Azizov", "Website": NSNull(),"About": NSNull()]

 func removeNSNull(from dict: [String: Any]) -> [String: Any] {
    var mutableDict = dict
    let keysWithEmptString = dict.filter { $0.1 is NSNull }.map { $0.0 }
    for key in keysWithEmptString {
        mutableDict[key] = ""
    }
    return mutableDict
}

使用：

let outputDict = removeNSNull(from: ["name": "Foo", "address": NSNull(), "id": "12"])

---

输出：[“名称”：“Foo”，“地址”：“id”：“12”]

Swift 4

比其他解决方案更有效一点。仅使用

O（n）

复杂性

extension Dictionary where Key == String, Value == Any? {

    var trimmingNullValues: [String: Any] {
        var copy = self
        forEach { (key, value) in
            if value == nil {
                copy.removeValue(forKey: key)
            }
        }
        return copy as [Key: ImplicitlyUnwrappedOptional<Value>]
    }
}

用法：
变量dict:[字符串：任何？]=[“确定”：无，“现在”：“k”，“foo”：无]
dict.trimNullValues（）//dict now:=[“now”：“k”]

使用reduce的Swift 4示例

let dictionary = [
  "Value": "Value",
  "Nil": nil
]

dictionary.reduce([String: String]()) { (dict, item) in

  guard let value = item.value else {
    return dict
  }

  var dict = dict
  dict[item.key] = value
  return dict
}

---

最干净的方法，只需一行

extension Dictionary {
    func filterNil() -> Dictionary {
        return self.filter { !($0.value is NSNull) }
    }
}

---

Swift 5添加了

compactMapValues（:）

，这样您就可以

let filteredDict = dict.compactMapValues { $0 is NSNull ? nil : $0 }

支持嵌套的

NSNull

要删除任何嵌套级别（包括数组和字典）中的任何

NSNull

外观，请尝试以下操作：

extension Dictionary where Key == String {
    func removeNullsFromDictionary() -> Self {
        var destination = Self()
        for key in self.keys {
            guard !(self[key] is NSNull) else { destination[key] = nil; continue }
            guard !(self[key] is Self) else { destination[key] = (self[key] as! Self).removeNullsFromDictionary() as? Value; continue }
            guard self[key] is [Value] else { destination[key] = self[key]; continue }

            let orgArray = self[key] as! [Value]
            var destArray: [Value] = []
            for item in orgArray {
                guard let this = item as? Self else { destArray.append(item); continue }
                destArray.append(this.removeNullsFromDictionary() as! Value)
            }
            destination[key] = destArray as? Value
        }
        return destination
    }
}

---

func nullkeyremovation（var dic:[String:AnyObject]）->[String:AnyObject]{为什么不在filter函数中更改条件，这样就可以得到包含所需数据的数组，而无需再次枚举：（{！（dic[$0]为NSNull）}）为什么在

Swift

中使用

NSDictionary

和

NSMutableDictionary

呢？函数名也应该以小写字母开头。此外，有很多强制展开操作可能会使代码崩溃，这个答案只适用于

String

键。可以，但只适用于embe不包含嵌入式阵列的dded字典这是一个有效的解决方案。